- Email: [email protected]
Morphology and ontogeny of Tuzoia bispinosa from the Kaili Biota (Cambrian Stage 5) of eastern Guizhou, China
Accepted Manuscript Title: Morphology and ontogeny of Tuzoia bispinosa from the Kaili Biota (Cambrian Stage 5) of eastern Guizhou, China Author: Rong-Qin Wen Yuan-Long Zhao Jin Peng PII: DOI: Reference:
S1871-174X(14)00084-5 http://dx.doi.org/doi:10.1016/j.palwor.2014.12.005 PALWOR 276
To appear in:
Palaeoworld
Received date: Revised date: Accepted date:
30-9-2014 28-11-2014 19-12-2014
Please cite this article as: Wen, R.-Q., Zhao, Y.-L., Peng, J.,Morphology and ontogeny of Tuzoia bispinosa from the Kaili Biota (Cambrian Stage 5) of eastern Guizhou, China, Palaeoworld (2014), http://dx.doi.org/10.1016/j.palwor.2014.12.005 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Morphology and ontogeny of Tuzoia bispinosa from the Kaili Biota (Cambrian Stage 5) of eastern Guizhou, China
ip t
Rong-Qin Wen, Yuan-Long Zhao, Jin Peng*
Guiyang 550003, China
us
* Corresponding author. E-mail address: [email protected]
cr
College of Resources and Environmental Engineering, Guizhou University,
an
Abstract
Tuzoia is a large bivalved arthropod having a wide geographic distribution in the
M
strata of the Cambrian Series 2 and 3. One species, Tuzoia bispinosa, is known from abundant material in the Kaili Biota (Cambrian Series 3, Stage 5). Based on 168
d
specimens from near Balang Village, Jianhe County, Guizhou Province, China, six ontogenetic stages of this species can be distinguished. In addition, the material
Ac ce p
te
provides information pertinent to interpreting the taphonomic history of T. bispinosa.
Keywords: Tuzoia; bivalved arthropod; ontogeny; Kaili Biota; Cambrian; China
1. Introduction
Tuzoia is the largest known bivalved Cambrian arthropod (Robison et al., in
press). Its carapace, with an extensive reticulate pattern, spiny margins, and lateral ridges, is unique among bivalved arthropods. Tuzoia is a genus in many of the
Burgess Shale-type biotas, occurring in the Cambrian Series 2 or 3 strata of North America, Europe, China, and Australia. Its occurrence in continental shelf environments, as well as in deep water slope areas, suggest that it was a swimming animal (Vannier et al., 2007). Due to its wide distribution, Tuzoia, has the potential to
Page 1 of 30
assist in intercontinental biostratigraphic correlation. The taxonomic position of Tuzoia has been controversial. Competing views of its classification are: 1, within the family Tuzoiidae, order Tuzoiida, class uncertain (Simonetta and Delle Cave, 1975; Hou, 1987; Vannier et al., 2007); 2, within the
ip t
Protocarididae (Robison and Richards, 1981); and 3, within an informal group of non-abdominal bivalved arthropods (Chen et al., 1996). Without details of the
cr
nonbiomineralized anatomy including the appendages, assignment to a family or order has been viewed as uncertain (Briggs et al., 1994; Shu et al., 1995). However,
us
the presence of a bivalved carapace suggests its placement in the class Crustacea. We accept this view here, assigning Tuzoia to the crustaceans, but leaving family and
an
order uncertain.
Tuzoia was first described (with T. retifera as the type species) by Walcott (1912)
M
from a single specimen collected from the Burgess Shale, British Columbia, at a level probably equivalent to the Raymond Quarry Shale Member (Walcott, 1912; Fletcher
d
and Collins, 1998). Subsequently, the type species Tuzoia retifera was redescribed by Resser (1929), based on more specimens that were collected by Walcott and others.
te
Resser (1929) erected three new species of Tuzoia, T. canadensis, T. burgessensis, and
Ac ce p
T. polleni. After that, Tuzoia was reported from various localities in North America (Endo and Resser, 1937; Resser and Howell, 1938; Briggs, 1977; Robison and Richards, 1981; Lieberman, 2003; Robison et al., in press), and in Australia, the Czech Republic, and China (Pan, 1957; Glaessner, 1979; Shu, 1990; Luo et al., 1999; Yuan and Zhao, 1999; Chlupáč and Kordule, 2002; Luo et al., 2006). More than 20 species of Tuzoia have been described. Vannier et al. (2007) studied Tuzoia worldwide, recognizing only seven species
named prior to 2006 as valid. Valid species Vannier et al. (2007) recognized are Tuzoia retifera Walcott, 1912; T. burgessensis Resser, 1929; T. canadensis Resser, 1929; T. polleni Resser, 1929; T. australis Glaessner, 1979; T. guntheri Robison and Richards, 1981; T. bispinosa Yuan and Zhao, 1999. Other Tuzoia species that also appear to be valid are T. tylodesa from the Cambrian Series 2 of Yunnan (Luo et al., 2006), and two undetermined but distinct species from the Czech Republic (Chlupáč
Page 2 of 30
and Kordule, 2002; Vannier et al., 2007). We follow Vannier et al. (2007) in synonymizing T. magna from the Kaili Biota with T. bispinosus. T. bispinosa is an important representative of the Kaili Biota (Cambrian Series 3). Large numbers of specimens of this species, including
ip t
ontogenetic material, provides important new information about the growth and evolution of this species. Yao et al. (2009) first recognized three ontogenetic stages of
cr
T. bispinosa. Here, on the basis of observational and statistical analyses of 168
specimens, we recognize six ontogenetic stages. We also comment on the taphonomy
an
us
of T. bispinosa.
2. Geological setting
M
The Kaili Formation represents part of the transitional slope belt between the Yangtze Platform and the Jiangnan Basin. It crops out widely through eastern
d
Guizhou (Zhou et al., 1979; Lu and Qian, 1983; Yin, 1987). The formation ranges in
te
thickness from 100 to 350 m, and consists mainly of grey-green silty mudstone plus calcareous mudstone and shale. In the lower and upper intervals it is interbedded with
Ac ce p
grey, thin-bed limestone. The Kaili Formation overlies thin to thick grey carbonate beds and interbedded shales of the Tsinghsutung Formation, and underlies light grey dolostone of the Jialao Formation. The Kaili Formation contains 62 genera of trilobites, and three polymerid trilobite biozones are recognized (Zhao et al., 2007, 2012a). In ascending order, the zones are Bathynotus kueichouensis-Ovatoryctocara cf. O. granulata Zone, Oryctocephalus indicus Zone, and Peronopsis taijiangensis Zone (Zhao et al., 2012a). The Wuliu-Zengjiayan Section of this formation, located on a mountain ridge behind Balang Village, Gedong Town, Jianhe County, has been proposed as a stratotype section for defining the base of the Cambrian Stage 5 (Zhao et al., 2007; Gaines et al., 2011; Sundberg et al., 2011). The Kaili Formation in this section is 214 m thick and the FAD of Oryctocephalus indicus, proposed as the primary tool for intercontinental correlation of the base of the Stage 5, occurs in 52.8
Page 3 of 30
m away from the base of the formation (Zhao et al., 2007, 2012b; Gaines et al., 2011; Sundberg et al., 2011). The Kaili Biota occurs in the Oryctocephalus indicus Zone and is characterized by the presence of corynexochid trilobites and gogiid eocrinoids (Zhao et al., 2005).
ip t
Up to now, the Kaili Biota has been found at five localities, Miaobanpo, Wuliu-Zenjianyan and, Jinyinshan sections near Balang Village (Zhao et al., 2005) ,
cr
Jianhe County; Sanwan section near Nangao, Danzhai County (Zhao et al., 2012c); and Zhuping section, Zhenyuan County (Yang, et al., 2011). The Miaobanpo section is
us
the most important locality of the Kaili Biota. Most of the nonbiomineralized fossils similar to those in the Chengjiang and Burgess Shale biotas, and some exquisite fossil
an
specimens, were collected from this section. Those specimens include abundant T. bispinosa. Because a fault occurs between the Tsinghsutung and Kaili formations at
M
the base of the Miaobanpo section, the lowermost part of the Kaili Formation is not exposed. The Kaili Formation in this section is only 156 m thick, and about 1.2 km
d
southwest of the Wuliu-Zengjiayan section (behind Balang Village, Fig. 1). All localities yield fossils of T. bispinosa.
te
More than 200 specimens of T. bispinosa have recently been collected from beds
Ac ce p
9 and 17 of the Miaobanpo section (Fig. 1c). Some specimens are partial or show diagenetic deformation. The new collections add to a large collection of material made in earlier years. Both older and newer collections have been used to study the ontogeny of T. bispinosa.
Fig. 1 here
All specimens described here are deposited in the Palaeontological Museum of Guizhou University, Guiyang, China. Specimens with the prefix GM were collected from the Miaobanpo Section of the Kaili Formation near Balang Village, Jianhe County, Guizhou Province, China. All the specimens described here are in the form of empty carapaces without appendages.
Page 4 of 30
3. Morphology and taxonomy of T. bispinosa Terminology. Morphological terms used for the description of Tuzoia follow Scott (1961), Briggs (1978), Robison and Richards (1981), Lieberman (2003), and Vannier
ip t
et al. (2007). Morphologic terminology of Tuzoia bispinosa and abbreviations used in
cr
the description are illustrated in Fig. 2.
us
Fig. 2 here
Tuzoia bispinosa was described by Yuan and Zhao (1999). The species shows a
an
medium sized valve, elliptical in outline, about 1.5 times longer than high; anterior and posterior cardinal processes are moderate and spinose; a lateral ridge extends almost the full length of the valve, slightly beneath mid-height; the valve surface is
M
covered by a reticulate pattern of fine ridges with small meshwork; two strong marginal spines are present in a postero-ventral position on each valve. The
d
postero-ventral spines are the basis for the species name “bispinosa” (see holotype,
te
Fig. 6E). Tuzoia magna Yuan and Zhao, 1999 was described as having two dorsal spines, short anterior and posterior cardinal processes, a faint lateral ridge, and three
Ac ce p
or four marginal spines in the postero-ventral position (see holotype, Fig. 8C). Subsequently, these presumed disparities were explained as the result of taphonomic factors, including compaction and different burial orientations. As a result, T. magna has been synonymized with T. bispinosa (Vannier et al., 2007). Ontogenetic data from T. bispinosa also support this conclusion (Yao et al., 2009).
4. Ontogenetic characters of T. bispinosa Ontogenetic changes in T. spinosa are illustrated in Fig. 3. Characters that change through ontogeny are: carapace outline, size of the reticulation, position of the lateral ridge, number and shape of spines along the carapace margin, and shape of the anterior and posterior cardinal processes. We studied 168 relatively complete
Page 5 of 30
specimens and discerned resulting in six obvious morphologic stages that we term early juvenile, late juvenile, early youth, late youth, early adult, and late adult stages (Fig. 3). The following descriptions apply to the morphology within these growth
ip t
intervals.
cr
Fig. 3 here
us
4.1. Early juvenile stage
Nine specimens were studied, and six specimens with typical characters are
an
illustrated (Fig. 4). Valve sub-ovoidal, small, length ranging from 9.8 to 13.5 mm, averaging 10.3 mm, height of valve varies between 7.8 and 11.8 mm, with the greatest height located near the mid-length of valve, antero-ventral area slightly contract to
M
oval, anterior front of valve slightly smaller than back of valve, L/H ratio about 1.14 to 1.25; lateral ridge developing, long range almost entire length of valve, near ventral
d
margin, located in position about 1/3 height of valve, almost parallel to ventral margin,
te
forward slightly vaulted upward; dorsal margin straight and long, acp broad at the base, long, tapering pointed and overhanging, constructing a relatively shallow
Ac ce p
anterior notch; pcp small, subtriangular in shape, slightly upwardly pointed, intersection angle (α) between pcp and dorsal margin approximately 27° to 43°; mps weakly developed (Fig. 4E), dorsal spines and ventral marginal spines absent; valve surface covered by complex reticulate pattern, but the reticulation varies, general diameter about 1.4 mm, reticulate pattern ill-defined or obliterated on some specimens, possibly caused by compaction or taphonomic deformation of the thin, nonbiomineralized carapace (Fig. 4A, B, D, E).
Fig. 4 here
4.2. Late juvenile stage
Page 6 of 30
Sixteen specimens were studied, and six specimens with typical characters are illustrated (Fig. 5). Valve medium size, ovoid, narrower anteriorly. Length of valve varies from 13.5 to 22.6 mm, height of valve 11.4 to 17.6 mm, highest point located close to back of valve; L/H ratio about 1.18 to 1.28; dorsal margin slightly convex
ip t
upward near mid-dorsal margin; compared to characters in the early juvenile stage,
acp and pcp are broadened at the base, acp is larger than pcp; anterior notch
cr
underneath acp with a prominent concavity, pvs developing, both pvs and mps long
and slender, ms absent, dorsal and ridge spines absent, lateral ridge prominent,
us
bulging, shortest length of valve with slight bend extending backward to back margin of valve, located underneath mps; anterior ventral part smaller than that of back
an
ventral, anterior ventral margin circular; dense reticulate pattern formed by adjacent polygonal meshwork, the number of polygonal sides varying from 4 to 7, generally
M
hexagonal, walls of the polygons are straight and narrow, diameter of mesh 0.8 to 2.1
Ac ce p
4.3. Early youth stage
te
Fig. 5 here
d
mm.
Fifty-three specimens were studied, and six specimens with typical characters are
illustrated (Fig. 6). Valve medium sized, elliptical, narrower anteriorly, greatest height is slightly behind mid-length, length of valve ranging from 19.6 to 36.4 mm, height of valve from 13.1 to 25.2 mm, L/H ratio about 1.45; carapace moderately vaulted; dorsal margin straight, 21.9 to 40.8 mm long (including acp and pcp); acp broad at the base, straight, long, forwardly pointing, longer than pcp, anterior notch under acp strongly concave, pcp broad in base, subtriangular and pointing slightly upwards, intersection angle (α) between pcp and dorsal margin approximately 30° to 55°. Both acp and pcp sharp in the tip; 2 to 3 small subtriangular dorsal spines along anterior third of dorsal margin, additional dorsal spines present along anterior half of dorsal margin; posterior ventral margin more swollen than anterior ventral margin; lr long,
Page 7 of 30
almost parallel to dorsal margin, prominent vaulted and position extending central length of valve, shorter than length of valve, located in mid-height of valve; both pvs and mps prominent and slender, pvs 2.5 to 3.8 mm in length; length of mps ranging from 2.2 to 3.7 mm; irregular reticulate pattern well-marked over surface of entire
ip t
valve, meshwork small on and around lr, reticulate pattern with small dense semi-round fossae on ventral marginal ridges, small and regular arrangement of ridges
cr
extending from ventral marginal ridges.
an
us
Fig. 6 here
4.4. Late youth stage
Forty-six specimens were studied, and illustrated by four specimens with typical
M
characters (Fig. 7). Valve long, elliptical, slightly narrower anteriorly; length of valve ranging from 36.2 to 54.7 mm, height of valve 23.3 to 42.9 mm, the greatest height
d
close to mid-length near posterior ventral margin; L/H ratio 1.27 to 1.54; carapace
te
strongly vaulted, lr located at the highest point of vaulted valve, showing a straight thick line, shortest length of valve at mid-height position of valve; dorsal margin
Ac ce p
straight, 39.4 to 58.4 mm long, including parts of acp and pcp; 2 thick dorsal spines present on anterior half of dorsal margin; acp shortened and widened at base compared with pcp and that of early youth stage; anterior notch under acp shallow compared to early youth stage; anterior ventral margin almost a vertical line with acp, near lr bent in an arc. These characters mark late youth development: lr thick and straight, located at the greatest height of vaulted carapace and shorter than length of valve, anterior end contracted backwards; well-marked reticulate pattern covers entire carapace, polygonal sides making up irregular meshwork, sides of mesh number 4 to 8, commonly 6-sided, maximum size of mesh, 3.6 mm, mesh on surface of valve larger, mesh on ventral margins and around acp small and dense.
Fig. 7 here
Page 8 of 30
4.5. Early adult stage Twenty-seven specimens were studied, and illustrated by 4 specimens with
ip t
typical characters (Fig. 8). Valve semicirclar in outline; length of valve ranging from 43.5 to 62.8 mm, height of valve 41.6 to 57.5 mm, the greatest height of valve located
cr
mid-length of valve, L/H ratio 1.05 to 1.09; carapace strongly vaulted; dm straight, 41.5 to 59.7 mm long, including acp and pcp, shortest length of valve, with several
us
thick and short zigzag dorsal spines on dorsal margin; acp and pcp short and broad at base; both anterior and posterior ventral margins vaulted forward, exceeding positions
an
of acp and pcp; acp and pcp short and small, pcp horizontally backwardly extended, intersection angle (α) between pcp and dorsal margin approximately 0° to 5°. lr thick and straight, located at the greatest height of vaulted carapace and mid-height of valve,
M
and shorter than length of valve; pvs and mps short and small, one or two ms along posterior margin; well-marked reticulate pattern covers the entire carapace, size of
Ac ce p
Fig. 8 here
te
to 8, commonly 6.
d
meshwork relative uniform, about 4.5 mm in diameter; sides of mesh number from 4
4.6. Late adult stage
Seventeen specimens were studied, and illustrated by 6 specimens with typical
characters (Fig. 9). Valve large, nearly round, slightly narrower anteriorly; length of valve ranging from 56.4 to 102.3 mm, height of valve 48.2 to 80.8 mm, the greatest height of valve located slightly backward of mid-length, L/H ratio 1.17 to 1.27; carapace strongly vaulted; dorsal margin straight, 54.9 to 97 mm long, including parts of acp and pcp, shortest length of valve, both anterior and posterior ventral margin vaulted forward, exceeding positions of acp and pcp, with 2 to 3 shorter dorsal spines and broad at the base on dorsal margin; acp and pcp smaller and weaker than early
Page 9 of 30
adult stage, anterior notch under acp shallower and weaker than early adult stage or even absent; lr straight, located centrally and at position of greatest height of vaulting, almost parallel to dorsal margin; pvs and mps equally short and small; reticulate pattern well-marked, covering the entire surface carapace, size of meshwork relatively
ip t
large and uniform, diameter 4 to 7 mm, smaller on ventral marginal ridges (Fig. 9).
us
cr
Fig. 9 here
5. General morphological variations during ontogeny
an
The ontogeny of T. bispinosa includes a presumed larva, followed by juvenile, youth, and adult stages. The post-larval ontogeny can be divided into six general
M
growth intervals. Valves shorter than 5 mm have not been found, so we do not have information about the earliest post-larval ontogeny. The six ontogenetic stages cover
d
length increase 9.8 mm (early juvenile stage) to 102.3 mm (late adult stage). Over this
te
ontogenetic range, the height of the valve increases (corresponding to length increase); valve in shape changes from ovate-narrow anteriorly through slightly narrower
Ac ce p
anteriorly, to semicircular with the position of the greatest height changing from close to the posterior ventral margin to mid-length; length and position of lateral ridges changes from extending the entire valve length (early juvenile stage) to away from the anterior ventral margin (late juvenile stage) to a transition away from both anterior and posterior ventral margins, located in the mid-part of the valve. At the same time, the position of the greatest point of carapace vaulting undergoes transition from the ventral margin to a position at mid-height of valve. Other changes during ontogeny are in the anterior and posterior cardinal processes; dorsal and ventral margin spines change, the former from slender, over the length of the valve (early juvenile-early youth stages), through short and thick, along the short length of the valve (late youth–early adult stages), to weak and thick, short (late adult stage); dorsal marginal spines change from absent (juvenile stage) to 2 or 3 small spines on a position near
Page 10 of 30
the anterior cardinal processes (early–adult stages); posterior ventral mid-spines and marginal spines change from weak, and small (juvenile stage) to prominent and long (early youth and late youth stages), to short and small (adult stage); a small secondary spine sometimes appears on the posterior ventral margin. The surface reticulation of T.
ip t
bispinosa changes through ontogeny. The reticulate pattern is dense and minute in
juvenile stages, becoming distinct and non-uniform in youth stages, and then
cr
becoming uniform and large in adult stages. As the number of reticulations decreases through ontogeny, their size increases. Due to differences in compaction, not all
us
specimens show these characters. Some complete specimens seem to lack mps, pvs, dms, and lr due to taphonomic factors. Therefore, the best means of identifying this
an
species is according to quantitative measures including the number and positions of margin spines, ratios of L/H, L/lr, L/DS, size of acp and pcp, mps and pvs. All
M
ontogenetic changes described above are confirmed by statistics (Fig. 10). Scatter plot diagrams of valve length versus height, lateral ridge length, dorsal margin length (Fig.
Ac ce p
Fig. 10 here
te
to 0.9908).
d
10A, B, C) all follow a linear relationship and show a strong correlation (R2= 0.9519
Acknowledgments
A special acknowledgment is given to Loren E. Babcock (Ohio State University, USA) for good revision and English correction in manuscript. We thank Bruce S. Lieberman (University of Kansas, USA) and an anonymous reviewer for their valuable comments and revising suggestions to early manuscript. This research was supported partly by grants from the Major State Basic Research Development Program of China (973 Program, No. 2013CB835002), the National Sciences Foundation of China (No. 41172005, No. 41330101, No. 41362002), the Key Project of International Cooperation of Guizhou Science and Technology Department (Gui. Co. 2010–7001),
Page 11 of 30
the Science, Technology and Education Talents from Governor of Guizhou Province (Gui. Sp. 2011–37), Research Centre of Paleontology of Guizhou (Gui, Sci. Z. [2014] 4003), Attracted Talent of Guizhou University (No. 2010021); Graduate Student
cr
Palaeontology Museum of the Shenzhen Xianhu Botanical Garden.
the
ip t
Innovation Fund of Guizhou University (Technology 2014020), and
us
References
Briggs, D.E.G., 1977. Bivalved arthropods from the Cambrian Burgess Shale of British Columbia. Palaeontology 22, 631-664.
an
Briggs, D.E.G., 1978. The morphology, mode of life, and affinities of Canadaspis perfecta (Crustacea: Phyllocarida), Middle Cambrian, Burgess Shale, British
M
Columbia. Philosophical Transactions of the Royal Society of London B 281, 439-487.
d
Briggs, D.E.G., Erwin, D.H., Collier, F.J., 1994. The Fossils of the Burgess Shale.
te
Smithsonian Institution Press, Washington, 238 pp. Chen, J.Y., Zhou, G.Q., Zhu, M.Y., Ye, G.Y., 1996. Chengjiang Biota — A Unique
Ac ce p
Window of the Cambrian Explosion. The National Museum of Natural Science, Taipei, 222 pp. (in Chinese).
Chlupăč, I., Kordule, V., 2002. Arthropods of Burgess Shale type from the Middle Cambrian of Bohemia (Czech Republic). Bulletin of the Czech Geological Survey 77, 167-182.
Endo, R., Resser, C.E., 1937. The Sinian and Cambrian formations and fossils of southern Manchoukuo. Bulletin of the Manchurian Science Museum 1, 1-406.
Fletcher, T.P., Collins, D., 1998. The Middle Cambrian Burgess Shale and its relationship to the Stephen Formation in the southern Canadian Rocky Mountains. Canadian Journal of Earth Sciences 35, 413-436. Gaines, R.R., Mering, J.A., Zhao, Y.L., Peng, J., 2011. Stratigraphic and microfacies analysis of Kaili Formation, a candidate GSSP for the Cambrian Series 2 —
Page 12 of 30
Series 3 boundary. Palaeogeolography, Palaoeclimatology, Palaeoecology 311, 171-183. Glanessner, M.F., 1979. Lower Cambrian Crustacea and annelid worms from Kangaroo Island, South Australia. Alcheringa 3, 21-31.
ip t
Hou, X.G., 1987. Early Cambrian large bivalved arthropods from Chengjiang, eastern Yunnan. Acta Palaeontologica Sinica 26 (3), 286-298 (in Chinese, with English
cr
summary).
Lieberman, B.S., 2003. A new soft-bodied fauna: The Pioche Formation of Nevada.
us
Journal of Paleontology 77, 674-690.
Lu, Y.H., Qian, Y.Y., 1983. On Cambrian trilobites’ character of western Hunan and
an
eastern Guizhou regions and significance in bio-geographcial realm division. In: The Editorial Committee of Theoretical Paleontology Books (Ed.), The
M
Bio-Geographcial Realm Division System in China. Science Press, Beijing, pp. 1-16 (in Chinese).
d
Luo, H.L., Hu, S.X., Chen, L.Z., Zhang, S.S., Tao, Y.H., 1999. Early Cambrian Chengjiang Fauna from Kunming Region, China. Yunnan Science and
te
Technology Press, Kunming, 162 pp. (in Chinese, with English summary).
Ac ce p
Luo, H.L., Fu, X.P., Hu, S.X., Li, Y., Chen, L.Z., You, T., Liu, Q., 2006. Bivalved arthropods form the early Cambrian Guanshan fauna in the Kunming and Wuding area. Acta Palaeontologica Sinica 45 (4), 460-472 (in Chinese, with English summary).
Pan, J., 1957. On the discovery of Homopoda from South China. Acta Palaeontologica Sinica 5 (4), 523-526 (in Chinese, with English abstract).
Resser, C.E., 1929. New Lower and Middle Cambrian Crustacea. Proceedings of the U.S. National Museum 76, 1-18. Resser, C.E., Howell, B.F., 1938. Lower Cambrian Olenellus Zone of the Appalachians. Geological Society of America Bulletin 49, 195-248.
Robison, R.A., Richards, B.C., 1981. Larger bivalve arthropods from the Middle Cambrian of Utah. Paleontological Contributions of the University of Kansas 106, 1-19.
Page 13 of 30
Robison, R.A., Babcock, L.E., Gunther, V.G., in press. Exceptional Cambrian Fossils from Utah: A Window into the Age of Trilobites. Utah Geological Survey, Salt Lake City. Scott, H.V., 1961. Shell morphology of Ostracoda. In: Moore, R.C., Teichert, C.
ip t
(Eds.), Treatise on Invertebrate Paleontology, Part Q, Arthropoda 3. Crustacea,
Ostracoda. Geological Society of America and University of Kansas Press,
cr
Lawrence, pp. Q21-Q43.
Shu, D.G., 1990. Cambrian and Lower Ordovician Bradoriida from Zhejiang, Hunan
us
and Shaanxi Provinces. Northwest University Press, Xi’an, 95 pp. (in Chinese, with English summary).
an
Shu, D.G., Zhang, X.L., Geyer, G., 1995. Anatomy and systematic affinities of the Lower Cambrian bivalved arthropod Isoxys auritus. Alcherlinga 19, 333-342.
M
Simonetta, A., Delle, C.L., 1975. The Cambrian non-trilobite arthropods from the Burgess Shale of British Columbia. A study of their comparative morphology,
d
taxonomy and evolutionary significance. Palaeontographica Italica 69 (39), 1-37. Sundberg, A.F., Zhao, Y.L., Yuan, J.L., Lin, J.P., 2011. Detailed trilobite
te
biostratigraphy across the proposed GSSP for Stage 5 (“Middle Cambrian”
Ac ce p
boundary) at the Wuliu-Zengjiaya section, Guizhou, China. Bulletin of Geosciences 86 (3), 423-464.
Vannier, J., Caron, J.B., Yuan, J.L., Briggs, D.E.G., Collins, D., Zhao, Y.L., Zhu, M.Y., 2007. Tuzoia: Morphology and lifestyle of a large bivalved arthropod of the Cambrian seas. Journal of Paleontology 81 (3), 445-471.
Walcott, C.D., 1912. Cambrian geology and paleontology II: Middle Cambrian Branchiopoda,
Malacostraca,
Trilobita
and
Merostomata.
Smithsonian
Miscellaneous Collections 57, 145-228. Yang, K.D., Zhao, Y.L., Yang, X.L., Da, Y., Wu, Z.T., 2011. Discovery of Kaili Biota from the Zhenyuan Area of Guizhou. Acta Palaeontological Sinica 50 (2), 176-187 (in Chinese, with English summary). Yao, L., Peng, J., Fu, X.P., Zhao, Y.L, 2009. Ontogeny of Tuzoia bispinosa from the Middle Cambrian Kaili (Guizhou, China) fauna. Acta Palaeontologica Sinica 48
Page 14 of 30
(1), 56-64 (in Chinese, with English summary). Yin, G.Z., 1987. Cambrian. In: Guizhou Bureau of Geology and Mineral Resources (Ed.), Regional Geology of Guizhou Province. Geological Publishing House, Beijing, pp. 49-96 (in Chinese, with English summary).
ip t
Yuan, J.L., Zhao, Y.L., 1999. Tuzoia (bivalved arthropods) from the Lower–Middle
(supplement) 88-93 (in Chinese, with English abstract).
cr
Cambrian Kaili Formation of Taijiang, Guizhou. Acta Palaeontologica Sinica 38,
Zhao, Y.L., Yang, R.D., Yuan, J.L., Zhu, M.Y., Guo, Q.J., Yang, X.L., Tai, T.S., 2001.
us
Cambrian stratigraphy at Balang, Guizhou Province, China: Candidate Section of a global unnamed and stratotype section for Taijiang Stage. Palaeoworld
an
13,189-208.
Zhao, Y.L., Zhu, M.Y., Babcock, L.E., Yuan, J.L., Parsley, R.L., Peng, J., Yang, X.L.,
M
Wang, Y., 2005. Kaili Biota: A taphonomic window on diversification of Metazoans from the basal Middle Cambrian: Guizhou, China. Acta Geologica
d
Sinica 79 (6), 751-765.
Zhao, Y.L, Yuan, J.L., Peng, S.C., Yang, X.L., Peng, J., Lin, J.P., Guo, Q.J., Wang,
te
Y.X., 2007. New data on the Wuliu-Zengjiaya section (Balang, South China),
Ac ce p
GSSP candidate for the base of Cambrian Series 3. Memoirs of Association of Australasian Palaeontologist 33, 57-65.
Zhao, Y.L., Peng, J., Yuan, J.L., Guo, Q.J., Tai, T.S., Yin, L.M., Parsley, L.R., Yang, Y.N., Yang, X.L., Zhang, P.X., 2012a. The Kaili Formation and Kaili Biota at the Wuliu-Zengjiaya section of Guizhou Province, China and proposed Global Standard Stratotype-section and Point (GSSP) of the unnamed Cambrian Series 3, Stage 5. Journal of Guizhou University 29 (supplement 1), 108-124.
Zhao, Y.L., Peng, J., Yuan, J.L., Babcock, L.E., Guo, Q.J., Yin, L.M., Yang, X.L., Tai, T.S., Wang, C.J., Lin, J.P., 2012b. Discussion of candidate stratotypes for GSSP defining the conterminous base of Cambrian provisional Series 3 and Stage 5. Journal of Guizhou University 29 (supplement 1), 35-48. Zhao, Y.L., Yang, Y.N., Peng, J., Yuan, J.L., Sun, H.J., Yan, X., 2012c. The Kaili Formation and Kaili Biota at the Sanwan Section in Guizhou Province, China
Page 15 of 30
and boundary between Cambrian Series 2/Series 3. Journal of Guizhou University 29 (supplement 1), 77-88. Zhou, Z.Y., Yuan, J.L., Zhang, Z.H., Wu, X.R., Yin, G.Z., 1979. Cambrian biogeographic zones of Guizhou and adjacent areas. Journal of Stratigrapy 3 (4),
cr
ip t
258-271 (in Chinese, with English summary).
us
Figures
an
Figure 1. Maps of Guizhou, South China, showing roads geologic features associated with the Kaili Biota localities near Balang and Tunzhou, Jianhe. (a) Map of the study
M
area. (b) Geologic map of Gedong region (after Zhao et al., 2001) and location of the Miaobanpo Section. (c) Stratigraphic column of Miaobanpo Section of the Kaili
d
Formation showing stratigraphic occurrences of Tuzoia bispinosa (stars).
te
Figure 2. Drawing showing general morphologic terminology of a valve (lateral view)
Ac ce p
of Tuzoia bispinosa (after Yuan and Zhao, 1999). Abbreviations of morphologic terms mostly follow Vannier et al. (2007). Abbreviations: A = distance between lateral ridge and dorsal margin; acp = anterior cardinal process; dm = dorsal margin; ds = dorsal spine; H = valve height (exclusive spines); L = valve length (exclusive spines); lr = lateral ridge; ms = marginal spine; pcp = posterior cardinal process; mps = midposterior spine; pvs = posteroventral spine; vm = ventral margin; (α) = angle
between posterior cardinal process and dorsal margin.
Figure 3. Reconstruction (lateral view) of morphologic characters for six ontogenetic stages of Tuzoia bispinosa Yuan and Zhao, 1999. (A) Early juvenile stage. (B) Late juvenile stage. (C) Early youth stage. (D) Late youth stage. (E) Early adult stage. (F) Late adult stage. Scale bar =10 mm. White arrow points anteriorly.
Page 16 of 30
Figure 4. Early juvenile stage of Tuzoia bispinosa (lateral view). (A) Right valve, lr located slightly under the mid-height, extends almost entire length of the valve; acp broad at the base, long and pointed, pcp small and pointing slightly upwards, GM 9-2-3361. (B) Left valve, a deformed specimen, showing lr extending enter valve,
ip t
bent to intersect angle in mid-length, valve nearly circular, acp and pcp on the dorsal margin constructing a intersect angle, GM 9-5-8961. (C) Right valve, deformed, lr
cr
extending whole valve, located under mid-height, near the ventral margin, dense
reticulate pattern covering surface of valve, anterior front of valve slightly small than
us
back of valve, GM9-2-3843. (D) Right valve, lr straight and located slightly below mid-height line, acp more prominent than pcp, GM 9-2-3330. (E) Left valve, small
an
carapace with ill-defined reticulate pattern, lr long, near ventral margin, slightly oblique to posterior margin, acp, pcp, mps pointed and slender, GM 9-4-2576. (F)
M
Specimen with clear reticulate pattern, lr strongly below the mid-height, near parallel to the ventral margin, acp only base to be seen due to compacted, GM-9-5-4201. All
d
scale bars = 5 mm. White arrow points anteriorly.
te
Figure 5. Late juvenile stage of Tuzoia bispinosa (lateral view). (A) Right valve,
Ac ce p
ill-defined reticulate pattern, lr long, shorter than length of valve, slightly bulging, the distal extending posterior ventral margin, located below mid-height, GM-13-1-188. (B) Left valve, dm slightly convex upward, acp broad in base, overhanging, a prominent anterior notch underneath acp, lr long, short length of valve, located below mid-height, the height located close to rear of valve, GM 9-3-4164. (C) Left valve, cover well-marked reticulate pattern, lr made unclear by compaction slightly below the mid-height, pvs and mps pointed and slender, GM-15-3-85. (D) Left valve, dm straight, lr made unclear by compaction slightly below the mid-height, GM9-5-3590. (E) Left valve, lr long, short the length of valve, lower the mid-height, bulging to extend to the posterior ventral margin, acp broad at the base, long and prominent than pcp, GM 9-5-1268. (F) Right valve, dm straight, lr slightly oblique to posterior margin, broad-based acp prominent and overhanging a relatively deep notch, GM 9-2-4982. All scale bars = 5 mm. White arrow points anteriorly.
Page 17 of 30
Figure 6. Early youth stage of Tuzoia bispinosa (lateral view). (A) Right valve, dm straight, acp more prominent than pcp and overhanging a deep notch, lr straight , pvs and mps pointed and slender, GM 14-1-226. (B) Right valve, lateral view, dm straight,
ip t
acp more prominent than pcp and overhanging a deep notch, lr prominent and slightly
oblique to posterior margin, mps, pvs pointed, GM 9-5-3529. (C) Left valve, dm
cr
zigzag with 5 short dorsal spins, lr prominent and straight, both acp and pcp
broad-based, GM 9-5-3514. (D) External mold of (E), GM 9-5-1541. (E) Right valve,
us
holotype of Tuzoia bispinosa Yuan and Zhao, 1999, dm straight, broad-based acp long, subtriangular pcp pointing slightly upwards, GM 9-5-1540. (F) Left valve, dm straight,
an
lr prominent and strong, reticulate pattern clearly marked and very small on valve
M
margin, GM 9-5-3417. All scale bars =5 mm. White arrow points anteriorly.
Figure 7. Late youth stage of Tuzoia bispinosa (lateral view). (A) Left valve, dm near
d
anterior acp with 3 incomplete zigzag blunt dorsal spines, lr straight, long and medium vaulted, immediately mid-height near vantral margin, mps and pvs
te
incomplete but the basement clearly marked, two small ms are weakly marked under
Ac ce p
the pvs, reticulate pattern clearly marked and small on the valve edge, GM 9-3-1798. (B) Right valve, dm straight, triangular acp broad in base, reticulate pattern clearly marked and small on the valve edge, lr prominent and slightly below the mid-height, GM 9-5-8960. (C) External mold of a right valve, lr straight and concave, mps and pvs clearly marked, reticulate pattern nearly uniform, GM-9-5-63. (D) Right valve, two blunt and upward dorsal spines along anterior margin, reticulate pattern well marked and small on the valve edge, lr prominent and long, GM 9-3-3791. (E) Left valve, two strong upward dorsal spines along the anterior dm, lr straight and prominent, short the length of valve, GM 9-5-7986. (F) Left valve, elliptical in outline, acp broad in base, lr straight and prominent, small sized reticulate pattern uniform, bases of mps and pvs clearly-marked, GM-9-3-3737. All scale bars = 10 mm. White arrow points anteriorly.
Page 18 of 30
Figure 8. Early adult stage of Tuzoia bispinosa (lateral view). (A) right valve, dm zigzag with six short, blunt dorsal spines, acp short and overhanging a shallow notch, pcp short and blunt, lr straight and only 2/3 length of valve, reticulate pattern clearly with hexagonal meshes, GM 9-3-3653. (B) Left valve, dm straight, 5 zigzag slightly
ip t
slanting forwardly spines on dm, lr straight, only 2/3 of valve length, reticulate pattern
uniformed with hexagonal meshes overall the valve, GM 17-4-1008. (C) Left valve,
cr
incomplete external mold, holotype of Tuzoia magna, dm straight and with two zigzag
short spines, approximately 1/3 length near acp; acp and pcp short, triangular in shape,
us
lr deformed by compacted, valve cover reticulate with hexagonal to elliptical meshes, GK-9-5-1552. (D) Right valve, dm straight, acp prominent than pcp, lr straight and
an
long, obvious short the length of valve located mid-height, the length of valve over the length of the dorsal margin (including acp and pcp); mps and pvs to be seen, pvs
M
prominent, reticulate pattern uniformed with small hexagonal meshes on surface valve, GM9-3-1153. (E) Left valve, dm straight, 5 short zigzag slightly slanting forwardly
d
spines along anterior dm , lr straight and only 2/3 of valve length, located position of the mid-height, also position of the greatest height vaulted valve, reticulate pattern
te
cover the valve uniformed with hexagonal meshes, pvs developing, GM 9-5-1248. (F)
Ac ce p
Right valve, six short, blunt spines on dm, approximately half length from acp, lr somewhat bent and only 2/3 of valve length by compacted, reticulate pattern covered valve uniformed with hexagonal meshes, GM-13-3-193a. All scale bars = 10 mm. White arrow points anteriorly.
Figure 9. Late adult stage of Tuzoia bispinosa (lateral view). (A) Left valve, only showing posterior part and to be seen obscure mps and pvs, a straight lr located mid-valve and the greatest height of vaulted carapace, with clear reticulate pattern uniformed of hexagonal to para-elliptical in shape, GM 9-5-1184. (B) Left valve, acp and pcp short and triangular, reticulate pattern and lr not clear due to taphonomic bias, one short and triangular pvs to be seen, GM 9-3-5017. (C) Incomplete right posterior lateral valve, the ventral margin swollen, pcp very blunt, pvs small, other fossils enrichment around lr, GM 9-2-3700. (D) Right valve, the ventral margin swollen, acp
Page 19 of 30
blunt, lr vestigial to less than half of valve length and can be seen, reticulate pattern with elliptical meshwork, pvs short and triangular, GM 9-2-1136. (E) Right valve, the valve transverse sub-spherical in outline, lr clearly marked with much more and much smaller meshes, the ventral margin swollen, GM 9-2-1128. (F) Left valve, the front
ip t
part of a specimen, to be seen near rounded antero-ventral margin, acp small and blunt, lr deformation by compacted, reticulate pattern cover surface of valve, common
cr
hexagonal meshes, GM 9-5-5901. All scale bars = 10 mm. White arrow points
us
anteriorly.
Figure10. (A) Scatter plot diagram of length versus width for 75 specimens of Tuzoia
an
bispinosa. (B) Scatter plot of length versus lateral ridge length on 62 specimens. (C) Scatter plot diagram of length versus dorsal margin length on 26 specimens.
M
Abbreviations: H = valve height; L = valve length; LR= lateral ridge length; DS =
Ac ce p
te
d
dorsal margin length; n = number of specimens.
Page 20 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 1
Page 21 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 2
Page 22 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 3
Page 23 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 4
Page 24 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 5
Page 25 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 6
Page 26 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 7
Page 27 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 8
Page 28 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 9
Page 29 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 10
Page 30 of 30
S1871-174X(14)00084-5 http://dx.doi.org/doi:10.1016/j.palwor.2014.12.005 PALWOR 276
To appear in:
Palaeoworld
Received date: Revised date: Accepted date:
30-9-2014 28-11-2014 19-12-2014
Please cite this article as: Wen, R.-Q., Zhao, Y.-L., Peng, J.,Morphology and ontogeny of Tuzoia bispinosa from the Kaili Biota (Cambrian Stage 5) of eastern Guizhou, China, Palaeoworld (2014), http://dx.doi.org/10.1016/j.palwor.2014.12.005 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Morphology and ontogeny of Tuzoia bispinosa from the Kaili Biota (Cambrian Stage 5) of eastern Guizhou, China
ip t
Rong-Qin Wen, Yuan-Long Zhao, Jin Peng*
Guiyang 550003, China
us
* Corresponding author. E-mail address: [email protected]
cr
College of Resources and Environmental Engineering, Guizhou University,
an
Abstract
Tuzoia is a large bivalved arthropod having a wide geographic distribution in the
M
strata of the Cambrian Series 2 and 3. One species, Tuzoia bispinosa, is known from abundant material in the Kaili Biota (Cambrian Series 3, Stage 5). Based on 168
d
specimens from near Balang Village, Jianhe County, Guizhou Province, China, six ontogenetic stages of this species can be distinguished. In addition, the material
Ac ce p
te
provides information pertinent to interpreting the taphonomic history of T. bispinosa.
Keywords: Tuzoia; bivalved arthropod; ontogeny; Kaili Biota; Cambrian; China
1. Introduction
Tuzoia is the largest known bivalved Cambrian arthropod (Robison et al., in
press). Its carapace, with an extensive reticulate pattern, spiny margins, and lateral ridges, is unique among bivalved arthropods. Tuzoia is a genus in many of the
Burgess Shale-type biotas, occurring in the Cambrian Series 2 or 3 strata of North America, Europe, China, and Australia. Its occurrence in continental shelf environments, as well as in deep water slope areas, suggest that it was a swimming animal (Vannier et al., 2007). Due to its wide distribution, Tuzoia, has the potential to
Page 1 of 30
assist in intercontinental biostratigraphic correlation. The taxonomic position of Tuzoia has been controversial. Competing views of its classification are: 1, within the family Tuzoiidae, order Tuzoiida, class uncertain (Simonetta and Delle Cave, 1975; Hou, 1987; Vannier et al., 2007); 2, within the
ip t
Protocarididae (Robison and Richards, 1981); and 3, within an informal group of non-abdominal bivalved arthropods (Chen et al., 1996). Without details of the
cr
nonbiomineralized anatomy including the appendages, assignment to a family or order has been viewed as uncertain (Briggs et al., 1994; Shu et al., 1995). However,
us
the presence of a bivalved carapace suggests its placement in the class Crustacea. We accept this view here, assigning Tuzoia to the crustaceans, but leaving family and
an
order uncertain.
Tuzoia was first described (with T. retifera as the type species) by Walcott (1912)
M
from a single specimen collected from the Burgess Shale, British Columbia, at a level probably equivalent to the Raymond Quarry Shale Member (Walcott, 1912; Fletcher
d
and Collins, 1998). Subsequently, the type species Tuzoia retifera was redescribed by Resser (1929), based on more specimens that were collected by Walcott and others.
te
Resser (1929) erected three new species of Tuzoia, T. canadensis, T. burgessensis, and
Ac ce p
T. polleni. After that, Tuzoia was reported from various localities in North America (Endo and Resser, 1937; Resser and Howell, 1938; Briggs, 1977; Robison and Richards, 1981; Lieberman, 2003; Robison et al., in press), and in Australia, the Czech Republic, and China (Pan, 1957; Glaessner, 1979; Shu, 1990; Luo et al., 1999; Yuan and Zhao, 1999; Chlupáč and Kordule, 2002; Luo et al., 2006). More than 20 species of Tuzoia have been described. Vannier et al. (2007) studied Tuzoia worldwide, recognizing only seven species
named prior to 2006 as valid. Valid species Vannier et al. (2007) recognized are Tuzoia retifera Walcott, 1912; T. burgessensis Resser, 1929; T. canadensis Resser, 1929; T. polleni Resser, 1929; T. australis Glaessner, 1979; T. guntheri Robison and Richards, 1981; T. bispinosa Yuan and Zhao, 1999. Other Tuzoia species that also appear to be valid are T. tylodesa from the Cambrian Series 2 of Yunnan (Luo et al., 2006), and two undetermined but distinct species from the Czech Republic (Chlupáč
Page 2 of 30
and Kordule, 2002; Vannier et al., 2007). We follow Vannier et al. (2007) in synonymizing T. magna from the Kaili Biota with T. bispinosus. T. bispinosa is an important representative of the Kaili Biota (Cambrian Series 3). Large numbers of specimens of this species, including
ip t
ontogenetic material, provides important new information about the growth and evolution of this species. Yao et al. (2009) first recognized three ontogenetic stages of
cr
T. bispinosa. Here, on the basis of observational and statistical analyses of 168
specimens, we recognize six ontogenetic stages. We also comment on the taphonomy
an
us
of T. bispinosa.
2. Geological setting
M
The Kaili Formation represents part of the transitional slope belt between the Yangtze Platform and the Jiangnan Basin. It crops out widely through eastern
d
Guizhou (Zhou et al., 1979; Lu and Qian, 1983; Yin, 1987). The formation ranges in
te
thickness from 100 to 350 m, and consists mainly of grey-green silty mudstone plus calcareous mudstone and shale. In the lower and upper intervals it is interbedded with
Ac ce p
grey, thin-bed limestone. The Kaili Formation overlies thin to thick grey carbonate beds and interbedded shales of the Tsinghsutung Formation, and underlies light grey dolostone of the Jialao Formation. The Kaili Formation contains 62 genera of trilobites, and three polymerid trilobite biozones are recognized (Zhao et al., 2007, 2012a). In ascending order, the zones are Bathynotus kueichouensis-Ovatoryctocara cf. O. granulata Zone, Oryctocephalus indicus Zone, and Peronopsis taijiangensis Zone (Zhao et al., 2012a). The Wuliu-Zengjiayan Section of this formation, located on a mountain ridge behind Balang Village, Gedong Town, Jianhe County, has been proposed as a stratotype section for defining the base of the Cambrian Stage 5 (Zhao et al., 2007; Gaines et al., 2011; Sundberg et al., 2011). The Kaili Formation in this section is 214 m thick and the FAD of Oryctocephalus indicus, proposed as the primary tool for intercontinental correlation of the base of the Stage 5, occurs in 52.8
Page 3 of 30
m away from the base of the formation (Zhao et al., 2007, 2012b; Gaines et al., 2011; Sundberg et al., 2011). The Kaili Biota occurs in the Oryctocephalus indicus Zone and is characterized by the presence of corynexochid trilobites and gogiid eocrinoids (Zhao et al., 2005).
ip t
Up to now, the Kaili Biota has been found at five localities, Miaobanpo, Wuliu-Zenjianyan and, Jinyinshan sections near Balang Village (Zhao et al., 2005) ,
cr
Jianhe County; Sanwan section near Nangao, Danzhai County (Zhao et al., 2012c); and Zhuping section, Zhenyuan County (Yang, et al., 2011). The Miaobanpo section is
us
the most important locality of the Kaili Biota. Most of the nonbiomineralized fossils similar to those in the Chengjiang and Burgess Shale biotas, and some exquisite fossil
an
specimens, were collected from this section. Those specimens include abundant T. bispinosa. Because a fault occurs between the Tsinghsutung and Kaili formations at
M
the base of the Miaobanpo section, the lowermost part of the Kaili Formation is not exposed. The Kaili Formation in this section is only 156 m thick, and about 1.2 km
d
southwest of the Wuliu-Zengjiayan section (behind Balang Village, Fig. 1). All localities yield fossils of T. bispinosa.
te
More than 200 specimens of T. bispinosa have recently been collected from beds
Ac ce p
9 and 17 of the Miaobanpo section (Fig. 1c). Some specimens are partial or show diagenetic deformation. The new collections add to a large collection of material made in earlier years. Both older and newer collections have been used to study the ontogeny of T. bispinosa.
Fig. 1 here
All specimens described here are deposited in the Palaeontological Museum of Guizhou University, Guiyang, China. Specimens with the prefix GM were collected from the Miaobanpo Section of the Kaili Formation near Balang Village, Jianhe County, Guizhou Province, China. All the specimens described here are in the form of empty carapaces without appendages.
Page 4 of 30
3. Morphology and taxonomy of T. bispinosa Terminology. Morphological terms used for the description of Tuzoia follow Scott (1961), Briggs (1978), Robison and Richards (1981), Lieberman (2003), and Vannier
ip t
et al. (2007). Morphologic terminology of Tuzoia bispinosa and abbreviations used in
cr
the description are illustrated in Fig. 2.
us
Fig. 2 here
Tuzoia bispinosa was described by Yuan and Zhao (1999). The species shows a
an
medium sized valve, elliptical in outline, about 1.5 times longer than high; anterior and posterior cardinal processes are moderate and spinose; a lateral ridge extends almost the full length of the valve, slightly beneath mid-height; the valve surface is
M
covered by a reticulate pattern of fine ridges with small meshwork; two strong marginal spines are present in a postero-ventral position on each valve. The
d
postero-ventral spines are the basis for the species name “bispinosa” (see holotype,
te
Fig. 6E). Tuzoia magna Yuan and Zhao, 1999 was described as having two dorsal spines, short anterior and posterior cardinal processes, a faint lateral ridge, and three
Ac ce p
or four marginal spines in the postero-ventral position (see holotype, Fig. 8C). Subsequently, these presumed disparities were explained as the result of taphonomic factors, including compaction and different burial orientations. As a result, T. magna has been synonymized with T. bispinosa (Vannier et al., 2007). Ontogenetic data from T. bispinosa also support this conclusion (Yao et al., 2009).
4. Ontogenetic characters of T. bispinosa Ontogenetic changes in T. spinosa are illustrated in Fig. 3. Characters that change through ontogeny are: carapace outline, size of the reticulation, position of the lateral ridge, number and shape of spines along the carapace margin, and shape of the anterior and posterior cardinal processes. We studied 168 relatively complete
Page 5 of 30
specimens and discerned resulting in six obvious morphologic stages that we term early juvenile, late juvenile, early youth, late youth, early adult, and late adult stages (Fig. 3). The following descriptions apply to the morphology within these growth
ip t
intervals.
cr
Fig. 3 here
us
4.1. Early juvenile stage
Nine specimens were studied, and six specimens with typical characters are
an
illustrated (Fig. 4). Valve sub-ovoidal, small, length ranging from 9.8 to 13.5 mm, averaging 10.3 mm, height of valve varies between 7.8 and 11.8 mm, with the greatest height located near the mid-length of valve, antero-ventral area slightly contract to
M
oval, anterior front of valve slightly smaller than back of valve, L/H ratio about 1.14 to 1.25; lateral ridge developing, long range almost entire length of valve, near ventral
d
margin, located in position about 1/3 height of valve, almost parallel to ventral margin,
te
forward slightly vaulted upward; dorsal margin straight and long, acp broad at the base, long, tapering pointed and overhanging, constructing a relatively shallow
Ac ce p
anterior notch; pcp small, subtriangular in shape, slightly upwardly pointed, intersection angle (α) between pcp and dorsal margin approximately 27° to 43°; mps weakly developed (Fig. 4E), dorsal spines and ventral marginal spines absent; valve surface covered by complex reticulate pattern, but the reticulation varies, general diameter about 1.4 mm, reticulate pattern ill-defined or obliterated on some specimens, possibly caused by compaction or taphonomic deformation of the thin, nonbiomineralized carapace (Fig. 4A, B, D, E).
Fig. 4 here
4.2. Late juvenile stage
Page 6 of 30
Sixteen specimens were studied, and six specimens with typical characters are illustrated (Fig. 5). Valve medium size, ovoid, narrower anteriorly. Length of valve varies from 13.5 to 22.6 mm, height of valve 11.4 to 17.6 mm, highest point located close to back of valve; L/H ratio about 1.18 to 1.28; dorsal margin slightly convex
ip t
upward near mid-dorsal margin; compared to characters in the early juvenile stage,
acp and pcp are broadened at the base, acp is larger than pcp; anterior notch
cr
underneath acp with a prominent concavity, pvs developing, both pvs and mps long
and slender, ms absent, dorsal and ridge spines absent, lateral ridge prominent,
us
bulging, shortest length of valve with slight bend extending backward to back margin of valve, located underneath mps; anterior ventral part smaller than that of back
an
ventral, anterior ventral margin circular; dense reticulate pattern formed by adjacent polygonal meshwork, the number of polygonal sides varying from 4 to 7, generally
M
hexagonal, walls of the polygons are straight and narrow, diameter of mesh 0.8 to 2.1
Ac ce p
4.3. Early youth stage
te
Fig. 5 here
d
mm.
Fifty-three specimens were studied, and six specimens with typical characters are
illustrated (Fig. 6). Valve medium sized, elliptical, narrower anteriorly, greatest height is slightly behind mid-length, length of valve ranging from 19.6 to 36.4 mm, height of valve from 13.1 to 25.2 mm, L/H ratio about 1.45; carapace moderately vaulted; dorsal margin straight, 21.9 to 40.8 mm long (including acp and pcp); acp broad at the base, straight, long, forwardly pointing, longer than pcp, anterior notch under acp strongly concave, pcp broad in base, subtriangular and pointing slightly upwards, intersection angle (α) between pcp and dorsal margin approximately 30° to 55°. Both acp and pcp sharp in the tip; 2 to 3 small subtriangular dorsal spines along anterior third of dorsal margin, additional dorsal spines present along anterior half of dorsal margin; posterior ventral margin more swollen than anterior ventral margin; lr long,
Page 7 of 30
almost parallel to dorsal margin, prominent vaulted and position extending central length of valve, shorter than length of valve, located in mid-height of valve; both pvs and mps prominent and slender, pvs 2.5 to 3.8 mm in length; length of mps ranging from 2.2 to 3.7 mm; irregular reticulate pattern well-marked over surface of entire
ip t
valve, meshwork small on and around lr, reticulate pattern with small dense semi-round fossae on ventral marginal ridges, small and regular arrangement of ridges
cr
extending from ventral marginal ridges.
an
us
Fig. 6 here
4.4. Late youth stage
Forty-six specimens were studied, and illustrated by four specimens with typical
M
characters (Fig. 7). Valve long, elliptical, slightly narrower anteriorly; length of valve ranging from 36.2 to 54.7 mm, height of valve 23.3 to 42.9 mm, the greatest height
d
close to mid-length near posterior ventral margin; L/H ratio 1.27 to 1.54; carapace
te
strongly vaulted, lr located at the highest point of vaulted valve, showing a straight thick line, shortest length of valve at mid-height position of valve; dorsal margin
Ac ce p
straight, 39.4 to 58.4 mm long, including parts of acp and pcp; 2 thick dorsal spines present on anterior half of dorsal margin; acp shortened and widened at base compared with pcp and that of early youth stage; anterior notch under acp shallow compared to early youth stage; anterior ventral margin almost a vertical line with acp, near lr bent in an arc. These characters mark late youth development: lr thick and straight, located at the greatest height of vaulted carapace and shorter than length of valve, anterior end contracted backwards; well-marked reticulate pattern covers entire carapace, polygonal sides making up irregular meshwork, sides of mesh number 4 to 8, commonly 6-sided, maximum size of mesh, 3.6 mm, mesh on surface of valve larger, mesh on ventral margins and around acp small and dense.
Fig. 7 here
Page 8 of 30
4.5. Early adult stage Twenty-seven specimens were studied, and illustrated by 4 specimens with
ip t
typical characters (Fig. 8). Valve semicirclar in outline; length of valve ranging from 43.5 to 62.8 mm, height of valve 41.6 to 57.5 mm, the greatest height of valve located
cr
mid-length of valve, L/H ratio 1.05 to 1.09; carapace strongly vaulted; dm straight, 41.5 to 59.7 mm long, including acp and pcp, shortest length of valve, with several
us
thick and short zigzag dorsal spines on dorsal margin; acp and pcp short and broad at base; both anterior and posterior ventral margins vaulted forward, exceeding positions
an
of acp and pcp; acp and pcp short and small, pcp horizontally backwardly extended, intersection angle (α) between pcp and dorsal margin approximately 0° to 5°. lr thick and straight, located at the greatest height of vaulted carapace and mid-height of valve,
M
and shorter than length of valve; pvs and mps short and small, one or two ms along posterior margin; well-marked reticulate pattern covers the entire carapace, size of
Ac ce p
Fig. 8 here
te
to 8, commonly 6.
d
meshwork relative uniform, about 4.5 mm in diameter; sides of mesh number from 4
4.6. Late adult stage
Seventeen specimens were studied, and illustrated by 6 specimens with typical
characters (Fig. 9). Valve large, nearly round, slightly narrower anteriorly; length of valve ranging from 56.4 to 102.3 mm, height of valve 48.2 to 80.8 mm, the greatest height of valve located slightly backward of mid-length, L/H ratio 1.17 to 1.27; carapace strongly vaulted; dorsal margin straight, 54.9 to 97 mm long, including parts of acp and pcp, shortest length of valve, both anterior and posterior ventral margin vaulted forward, exceeding positions of acp and pcp, with 2 to 3 shorter dorsal spines and broad at the base on dorsal margin; acp and pcp smaller and weaker than early
Page 9 of 30
adult stage, anterior notch under acp shallower and weaker than early adult stage or even absent; lr straight, located centrally and at position of greatest height of vaulting, almost parallel to dorsal margin; pvs and mps equally short and small; reticulate pattern well-marked, covering the entire surface carapace, size of meshwork relatively
ip t
large and uniform, diameter 4 to 7 mm, smaller on ventral marginal ridges (Fig. 9).
us
cr
Fig. 9 here
5. General morphological variations during ontogeny
an
The ontogeny of T. bispinosa includes a presumed larva, followed by juvenile, youth, and adult stages. The post-larval ontogeny can be divided into six general
M
growth intervals. Valves shorter than 5 mm have not been found, so we do not have information about the earliest post-larval ontogeny. The six ontogenetic stages cover
d
length increase 9.8 mm (early juvenile stage) to 102.3 mm (late adult stage). Over this
te
ontogenetic range, the height of the valve increases (corresponding to length increase); valve in shape changes from ovate-narrow anteriorly through slightly narrower
Ac ce p
anteriorly, to semicircular with the position of the greatest height changing from close to the posterior ventral margin to mid-length; length and position of lateral ridges changes from extending the entire valve length (early juvenile stage) to away from the anterior ventral margin (late juvenile stage) to a transition away from both anterior and posterior ventral margins, located in the mid-part of the valve. At the same time, the position of the greatest point of carapace vaulting undergoes transition from the ventral margin to a position at mid-height of valve. Other changes during ontogeny are in the anterior and posterior cardinal processes; dorsal and ventral margin spines change, the former from slender, over the length of the valve (early juvenile-early youth stages), through short and thick, along the short length of the valve (late youth–early adult stages), to weak and thick, short (late adult stage); dorsal marginal spines change from absent (juvenile stage) to 2 or 3 small spines on a position near
Page 10 of 30
the anterior cardinal processes (early–adult stages); posterior ventral mid-spines and marginal spines change from weak, and small (juvenile stage) to prominent and long (early youth and late youth stages), to short and small (adult stage); a small secondary spine sometimes appears on the posterior ventral margin. The surface reticulation of T.
ip t
bispinosa changes through ontogeny. The reticulate pattern is dense and minute in
juvenile stages, becoming distinct and non-uniform in youth stages, and then
cr
becoming uniform and large in adult stages. As the number of reticulations decreases through ontogeny, their size increases. Due to differences in compaction, not all
us
specimens show these characters. Some complete specimens seem to lack mps, pvs, dms, and lr due to taphonomic factors. Therefore, the best means of identifying this
an
species is according to quantitative measures including the number and positions of margin spines, ratios of L/H, L/lr, L/DS, size of acp and pcp, mps and pvs. All
M
ontogenetic changes described above are confirmed by statistics (Fig. 10). Scatter plot diagrams of valve length versus height, lateral ridge length, dorsal margin length (Fig.
Ac ce p
Fig. 10 here
te
to 0.9908).
d
10A, B, C) all follow a linear relationship and show a strong correlation (R2= 0.9519
Acknowledgments
A special acknowledgment is given to Loren E. Babcock (Ohio State University, USA) for good revision and English correction in manuscript. We thank Bruce S. Lieberman (University of Kansas, USA) and an anonymous reviewer for their valuable comments and revising suggestions to early manuscript. This research was supported partly by grants from the Major State Basic Research Development Program of China (973 Program, No. 2013CB835002), the National Sciences Foundation of China (No. 41172005, No. 41330101, No. 41362002), the Key Project of International Cooperation of Guizhou Science and Technology Department (Gui. Co. 2010–7001),
Page 11 of 30
the Science, Technology and Education Talents from Governor of Guizhou Province (Gui. Sp. 2011–37), Research Centre of Paleontology of Guizhou (Gui, Sci. Z. [2014] 4003), Attracted Talent of Guizhou University (No. 2010021); Graduate Student
cr
Palaeontology Museum of the Shenzhen Xianhu Botanical Garden.
the
ip t
Innovation Fund of Guizhou University (Technology 2014020), and
us
References
Briggs, D.E.G., 1977. Bivalved arthropods from the Cambrian Burgess Shale of British Columbia. Palaeontology 22, 631-664.
an
Briggs, D.E.G., 1978. The morphology, mode of life, and affinities of Canadaspis perfecta (Crustacea: Phyllocarida), Middle Cambrian, Burgess Shale, British
M
Columbia. Philosophical Transactions of the Royal Society of London B 281, 439-487.
d
Briggs, D.E.G., Erwin, D.H., Collier, F.J., 1994. The Fossils of the Burgess Shale.
te
Smithsonian Institution Press, Washington, 238 pp. Chen, J.Y., Zhou, G.Q., Zhu, M.Y., Ye, G.Y., 1996. Chengjiang Biota — A Unique
Ac ce p
Window of the Cambrian Explosion. The National Museum of Natural Science, Taipei, 222 pp. (in Chinese).
Chlupăč, I., Kordule, V., 2002. Arthropods of Burgess Shale type from the Middle Cambrian of Bohemia (Czech Republic). Bulletin of the Czech Geological Survey 77, 167-182.
Endo, R., Resser, C.E., 1937. The Sinian and Cambrian formations and fossils of southern Manchoukuo. Bulletin of the Manchurian Science Museum 1, 1-406.
Fletcher, T.P., Collins, D., 1998. The Middle Cambrian Burgess Shale and its relationship to the Stephen Formation in the southern Canadian Rocky Mountains. Canadian Journal of Earth Sciences 35, 413-436. Gaines, R.R., Mering, J.A., Zhao, Y.L., Peng, J., 2011. Stratigraphic and microfacies analysis of Kaili Formation, a candidate GSSP for the Cambrian Series 2 —
Page 12 of 30
Series 3 boundary. Palaeogeolography, Palaoeclimatology, Palaeoecology 311, 171-183. Glanessner, M.F., 1979. Lower Cambrian Crustacea and annelid worms from Kangaroo Island, South Australia. Alcheringa 3, 21-31.
ip t
Hou, X.G., 1987. Early Cambrian large bivalved arthropods from Chengjiang, eastern Yunnan. Acta Palaeontologica Sinica 26 (3), 286-298 (in Chinese, with English
cr
summary).
Lieberman, B.S., 2003. A new soft-bodied fauna: The Pioche Formation of Nevada.
us
Journal of Paleontology 77, 674-690.
Lu, Y.H., Qian, Y.Y., 1983. On Cambrian trilobites’ character of western Hunan and
an
eastern Guizhou regions and significance in bio-geographcial realm division. In: The Editorial Committee of Theoretical Paleontology Books (Ed.), The
M
Bio-Geographcial Realm Division System in China. Science Press, Beijing, pp. 1-16 (in Chinese).
d
Luo, H.L., Hu, S.X., Chen, L.Z., Zhang, S.S., Tao, Y.H., 1999. Early Cambrian Chengjiang Fauna from Kunming Region, China. Yunnan Science and
te
Technology Press, Kunming, 162 pp. (in Chinese, with English summary).
Ac ce p
Luo, H.L., Fu, X.P., Hu, S.X., Li, Y., Chen, L.Z., You, T., Liu, Q., 2006. Bivalved arthropods form the early Cambrian Guanshan fauna in the Kunming and Wuding area. Acta Palaeontologica Sinica 45 (4), 460-472 (in Chinese, with English summary).
Pan, J., 1957. On the discovery of Homopoda from South China. Acta Palaeontologica Sinica 5 (4), 523-526 (in Chinese, with English abstract).
Resser, C.E., 1929. New Lower and Middle Cambrian Crustacea. Proceedings of the U.S. National Museum 76, 1-18. Resser, C.E., Howell, B.F., 1938. Lower Cambrian Olenellus Zone of the Appalachians. Geological Society of America Bulletin 49, 195-248.
Robison, R.A., Richards, B.C., 1981. Larger bivalve arthropods from the Middle Cambrian of Utah. Paleontological Contributions of the University of Kansas 106, 1-19.
Page 13 of 30
Robison, R.A., Babcock, L.E., Gunther, V.G., in press. Exceptional Cambrian Fossils from Utah: A Window into the Age of Trilobites. Utah Geological Survey, Salt Lake City. Scott, H.V., 1961. Shell morphology of Ostracoda. In: Moore, R.C., Teichert, C.
ip t
(Eds.), Treatise on Invertebrate Paleontology, Part Q, Arthropoda 3. Crustacea,
Ostracoda. Geological Society of America and University of Kansas Press,
cr
Lawrence, pp. Q21-Q43.
Shu, D.G., 1990. Cambrian and Lower Ordovician Bradoriida from Zhejiang, Hunan
us
and Shaanxi Provinces. Northwest University Press, Xi’an, 95 pp. (in Chinese, with English summary).
an
Shu, D.G., Zhang, X.L., Geyer, G., 1995. Anatomy and systematic affinities of the Lower Cambrian bivalved arthropod Isoxys auritus. Alcherlinga 19, 333-342.
M
Simonetta, A., Delle, C.L., 1975. The Cambrian non-trilobite arthropods from the Burgess Shale of British Columbia. A study of their comparative morphology,
d
taxonomy and evolutionary significance. Palaeontographica Italica 69 (39), 1-37. Sundberg, A.F., Zhao, Y.L., Yuan, J.L., Lin, J.P., 2011. Detailed trilobite
te
biostratigraphy across the proposed GSSP for Stage 5 (“Middle Cambrian”
Ac ce p
boundary) at the Wuliu-Zengjiaya section, Guizhou, China. Bulletin of Geosciences 86 (3), 423-464.
Vannier, J., Caron, J.B., Yuan, J.L., Briggs, D.E.G., Collins, D., Zhao, Y.L., Zhu, M.Y., 2007. Tuzoia: Morphology and lifestyle of a large bivalved arthropod of the Cambrian seas. Journal of Paleontology 81 (3), 445-471.
Walcott, C.D., 1912. Cambrian geology and paleontology II: Middle Cambrian Branchiopoda,
Malacostraca,
Trilobita
and
Merostomata.
Smithsonian
Miscellaneous Collections 57, 145-228. Yang, K.D., Zhao, Y.L., Yang, X.L., Da, Y., Wu, Z.T., 2011. Discovery of Kaili Biota from the Zhenyuan Area of Guizhou. Acta Palaeontological Sinica 50 (2), 176-187 (in Chinese, with English summary). Yao, L., Peng, J., Fu, X.P., Zhao, Y.L, 2009. Ontogeny of Tuzoia bispinosa from the Middle Cambrian Kaili (Guizhou, China) fauna. Acta Palaeontologica Sinica 48
Page 14 of 30
(1), 56-64 (in Chinese, with English summary). Yin, G.Z., 1987. Cambrian. In: Guizhou Bureau of Geology and Mineral Resources (Ed.), Regional Geology of Guizhou Province. Geological Publishing House, Beijing, pp. 49-96 (in Chinese, with English summary).
ip t
Yuan, J.L., Zhao, Y.L., 1999. Tuzoia (bivalved arthropods) from the Lower–Middle
(supplement) 88-93 (in Chinese, with English abstract).
cr
Cambrian Kaili Formation of Taijiang, Guizhou. Acta Palaeontologica Sinica 38,
Zhao, Y.L., Yang, R.D., Yuan, J.L., Zhu, M.Y., Guo, Q.J., Yang, X.L., Tai, T.S., 2001.
us
Cambrian stratigraphy at Balang, Guizhou Province, China: Candidate Section of a global unnamed and stratotype section for Taijiang Stage. Palaeoworld
an
13,189-208.
Zhao, Y.L., Zhu, M.Y., Babcock, L.E., Yuan, J.L., Parsley, R.L., Peng, J., Yang, X.L.,
M
Wang, Y., 2005. Kaili Biota: A taphonomic window on diversification of Metazoans from the basal Middle Cambrian: Guizhou, China. Acta Geologica
d
Sinica 79 (6), 751-765.
Zhao, Y.L, Yuan, J.L., Peng, S.C., Yang, X.L., Peng, J., Lin, J.P., Guo, Q.J., Wang,
te
Y.X., 2007. New data on the Wuliu-Zengjiaya section (Balang, South China),
Ac ce p
GSSP candidate for the base of Cambrian Series 3. Memoirs of Association of Australasian Palaeontologist 33, 57-65.
Zhao, Y.L., Peng, J., Yuan, J.L., Guo, Q.J., Tai, T.S., Yin, L.M., Parsley, L.R., Yang, Y.N., Yang, X.L., Zhang, P.X., 2012a. The Kaili Formation and Kaili Biota at the Wuliu-Zengjiaya section of Guizhou Province, China and proposed Global Standard Stratotype-section and Point (GSSP) of the unnamed Cambrian Series 3, Stage 5. Journal of Guizhou University 29 (supplement 1), 108-124.
Zhao, Y.L., Peng, J., Yuan, J.L., Babcock, L.E., Guo, Q.J., Yin, L.M., Yang, X.L., Tai, T.S., Wang, C.J., Lin, J.P., 2012b. Discussion of candidate stratotypes for GSSP defining the conterminous base of Cambrian provisional Series 3 and Stage 5. Journal of Guizhou University 29 (supplement 1), 35-48. Zhao, Y.L., Yang, Y.N., Peng, J., Yuan, J.L., Sun, H.J., Yan, X., 2012c. The Kaili Formation and Kaili Biota at the Sanwan Section in Guizhou Province, China
Page 15 of 30
and boundary between Cambrian Series 2/Series 3. Journal of Guizhou University 29 (supplement 1), 77-88. Zhou, Z.Y., Yuan, J.L., Zhang, Z.H., Wu, X.R., Yin, G.Z., 1979. Cambrian biogeographic zones of Guizhou and adjacent areas. Journal of Stratigrapy 3 (4),
cr
ip t
258-271 (in Chinese, with English summary).
us
Figures
an
Figure 1. Maps of Guizhou, South China, showing roads geologic features associated with the Kaili Biota localities near Balang and Tunzhou, Jianhe. (a) Map of the study
M
area. (b) Geologic map of Gedong region (after Zhao et al., 2001) and location of the Miaobanpo Section. (c) Stratigraphic column of Miaobanpo Section of the Kaili
d
Formation showing stratigraphic occurrences of Tuzoia bispinosa (stars).
te
Figure 2. Drawing showing general morphologic terminology of a valve (lateral view)
Ac ce p
of Tuzoia bispinosa (after Yuan and Zhao, 1999). Abbreviations of morphologic terms mostly follow Vannier et al. (2007). Abbreviations: A = distance between lateral ridge and dorsal margin; acp = anterior cardinal process; dm = dorsal margin; ds = dorsal spine; H = valve height (exclusive spines); L = valve length (exclusive spines); lr = lateral ridge; ms = marginal spine; pcp = posterior cardinal process; mps = midposterior spine; pvs = posteroventral spine; vm = ventral margin; (α) = angle
between posterior cardinal process and dorsal margin.
Figure 3. Reconstruction (lateral view) of morphologic characters for six ontogenetic stages of Tuzoia bispinosa Yuan and Zhao, 1999. (A) Early juvenile stage. (B) Late juvenile stage. (C) Early youth stage. (D) Late youth stage. (E) Early adult stage. (F) Late adult stage. Scale bar =10 mm. White arrow points anteriorly.
Page 16 of 30
Figure 4. Early juvenile stage of Tuzoia bispinosa (lateral view). (A) Right valve, lr located slightly under the mid-height, extends almost entire length of the valve; acp broad at the base, long and pointed, pcp small and pointing slightly upwards, GM 9-2-3361. (B) Left valve, a deformed specimen, showing lr extending enter valve,
ip t
bent to intersect angle in mid-length, valve nearly circular, acp and pcp on the dorsal margin constructing a intersect angle, GM 9-5-8961. (C) Right valve, deformed, lr
cr
extending whole valve, located under mid-height, near the ventral margin, dense
reticulate pattern covering surface of valve, anterior front of valve slightly small than
us
back of valve, GM9-2-3843. (D) Right valve, lr straight and located slightly below mid-height line, acp more prominent than pcp, GM 9-2-3330. (E) Left valve, small
an
carapace with ill-defined reticulate pattern, lr long, near ventral margin, slightly oblique to posterior margin, acp, pcp, mps pointed and slender, GM 9-4-2576. (F)
M
Specimen with clear reticulate pattern, lr strongly below the mid-height, near parallel to the ventral margin, acp only base to be seen due to compacted, GM-9-5-4201. All
d
scale bars = 5 mm. White arrow points anteriorly.
te
Figure 5. Late juvenile stage of Tuzoia bispinosa (lateral view). (A) Right valve,
Ac ce p
ill-defined reticulate pattern, lr long, shorter than length of valve, slightly bulging, the distal extending posterior ventral margin, located below mid-height, GM-13-1-188. (B) Left valve, dm slightly convex upward, acp broad in base, overhanging, a prominent anterior notch underneath acp, lr long, short length of valve, located below mid-height, the height located close to rear of valve, GM 9-3-4164. (C) Left valve, cover well-marked reticulate pattern, lr made unclear by compaction slightly below the mid-height, pvs and mps pointed and slender, GM-15-3-85. (D) Left valve, dm straight, lr made unclear by compaction slightly below the mid-height, GM9-5-3590. (E) Left valve, lr long, short the length of valve, lower the mid-height, bulging to extend to the posterior ventral margin, acp broad at the base, long and prominent than pcp, GM 9-5-1268. (F) Right valve, dm straight, lr slightly oblique to posterior margin, broad-based acp prominent and overhanging a relatively deep notch, GM 9-2-4982. All scale bars = 5 mm. White arrow points anteriorly.
Page 17 of 30
Figure 6. Early youth stage of Tuzoia bispinosa (lateral view). (A) Right valve, dm straight, acp more prominent than pcp and overhanging a deep notch, lr straight , pvs and mps pointed and slender, GM 14-1-226. (B) Right valve, lateral view, dm straight,
ip t
acp more prominent than pcp and overhanging a deep notch, lr prominent and slightly
oblique to posterior margin, mps, pvs pointed, GM 9-5-3529. (C) Left valve, dm
cr
zigzag with 5 short dorsal spins, lr prominent and straight, both acp and pcp
broad-based, GM 9-5-3514. (D) External mold of (E), GM 9-5-1541. (E) Right valve,
us
holotype of Tuzoia bispinosa Yuan and Zhao, 1999, dm straight, broad-based acp long, subtriangular pcp pointing slightly upwards, GM 9-5-1540. (F) Left valve, dm straight,
an
lr prominent and strong, reticulate pattern clearly marked and very small on valve
M
margin, GM 9-5-3417. All scale bars =5 mm. White arrow points anteriorly.
Figure 7. Late youth stage of Tuzoia bispinosa (lateral view). (A) Left valve, dm near
d
anterior acp with 3 incomplete zigzag blunt dorsal spines, lr straight, long and medium vaulted, immediately mid-height near vantral margin, mps and pvs
te
incomplete but the basement clearly marked, two small ms are weakly marked under
Ac ce p
the pvs, reticulate pattern clearly marked and small on the valve edge, GM 9-3-1798. (B) Right valve, dm straight, triangular acp broad in base, reticulate pattern clearly marked and small on the valve edge, lr prominent and slightly below the mid-height, GM 9-5-8960. (C) External mold of a right valve, lr straight and concave, mps and pvs clearly marked, reticulate pattern nearly uniform, GM-9-5-63. (D) Right valve, two blunt and upward dorsal spines along anterior margin, reticulate pattern well marked and small on the valve edge, lr prominent and long, GM 9-3-3791. (E) Left valve, two strong upward dorsal spines along the anterior dm, lr straight and prominent, short the length of valve, GM 9-5-7986. (F) Left valve, elliptical in outline, acp broad in base, lr straight and prominent, small sized reticulate pattern uniform, bases of mps and pvs clearly-marked, GM-9-3-3737. All scale bars = 10 mm. White arrow points anteriorly.
Page 18 of 30
Figure 8. Early adult stage of Tuzoia bispinosa (lateral view). (A) right valve, dm zigzag with six short, blunt dorsal spines, acp short and overhanging a shallow notch, pcp short and blunt, lr straight and only 2/3 length of valve, reticulate pattern clearly with hexagonal meshes, GM 9-3-3653. (B) Left valve, dm straight, 5 zigzag slightly
ip t
slanting forwardly spines on dm, lr straight, only 2/3 of valve length, reticulate pattern
uniformed with hexagonal meshes overall the valve, GM 17-4-1008. (C) Left valve,
cr
incomplete external mold, holotype of Tuzoia magna, dm straight and with two zigzag
short spines, approximately 1/3 length near acp; acp and pcp short, triangular in shape,
us
lr deformed by compacted, valve cover reticulate with hexagonal to elliptical meshes, GK-9-5-1552. (D) Right valve, dm straight, acp prominent than pcp, lr straight and
an
long, obvious short the length of valve located mid-height, the length of valve over the length of the dorsal margin (including acp and pcp); mps and pvs to be seen, pvs
M
prominent, reticulate pattern uniformed with small hexagonal meshes on surface valve, GM9-3-1153. (E) Left valve, dm straight, 5 short zigzag slightly slanting forwardly
d
spines along anterior dm , lr straight and only 2/3 of valve length, located position of the mid-height, also position of the greatest height vaulted valve, reticulate pattern
te
cover the valve uniformed with hexagonal meshes, pvs developing, GM 9-5-1248. (F)
Ac ce p
Right valve, six short, blunt spines on dm, approximately half length from acp, lr somewhat bent and only 2/3 of valve length by compacted, reticulate pattern covered valve uniformed with hexagonal meshes, GM-13-3-193a. All scale bars = 10 mm. White arrow points anteriorly.
Figure 9. Late adult stage of Tuzoia bispinosa (lateral view). (A) Left valve, only showing posterior part and to be seen obscure mps and pvs, a straight lr located mid-valve and the greatest height of vaulted carapace, with clear reticulate pattern uniformed of hexagonal to para-elliptical in shape, GM 9-5-1184. (B) Left valve, acp and pcp short and triangular, reticulate pattern and lr not clear due to taphonomic bias, one short and triangular pvs to be seen, GM 9-3-5017. (C) Incomplete right posterior lateral valve, the ventral margin swollen, pcp very blunt, pvs small, other fossils enrichment around lr, GM 9-2-3700. (D) Right valve, the ventral margin swollen, acp
Page 19 of 30
blunt, lr vestigial to less than half of valve length and can be seen, reticulate pattern with elliptical meshwork, pvs short and triangular, GM 9-2-1136. (E) Right valve, the valve transverse sub-spherical in outline, lr clearly marked with much more and much smaller meshes, the ventral margin swollen, GM 9-2-1128. (F) Left valve, the front
ip t
part of a specimen, to be seen near rounded antero-ventral margin, acp small and blunt, lr deformation by compacted, reticulate pattern cover surface of valve, common
cr
hexagonal meshes, GM 9-5-5901. All scale bars = 10 mm. White arrow points
us
anteriorly.
Figure10. (A) Scatter plot diagram of length versus width for 75 specimens of Tuzoia
an
bispinosa. (B) Scatter plot of length versus lateral ridge length on 62 specimens. (C) Scatter plot diagram of length versus dorsal margin length on 26 specimens.
M
Abbreviations: H = valve height; L = valve length; LR= lateral ridge length; DS =
Ac ce p
te
d
dorsal margin length; n = number of specimens.
Page 20 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 1
Page 21 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 2
Page 22 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 3
Page 23 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 4
Page 24 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 5
Page 25 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 6
Page 26 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 7
Page 27 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 8
Page 28 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 9
Page 29 of 30
Ac
ce
pt
ed
M
an
us
cr
i
Figure 10
Page 30 of 30