New turtle egg fossil from the Upper Cretaceous of the Laiyang Basin, Shandong Province, China

WANG, QIANG; WANG, XIAOLIN; ZHAO, ZIKUI; ZHANG, JIALIANG; JIANG, SHUNXING

doi:10.1590/S0001-37652013000100008

QIANG WANG

Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China

XIAOLIN WANG

Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China

ZIKUI ZHAO

Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China

JIALIANG ZHANG

Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China

University of Chinese Academy of Sciences, Beijing, China

SHUNXING JIANG

Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China

University of Chinese Academy of Sciences, Beijing, China

Correspondence to: Xiaolin Wang, E-mail: wangxiaolin@ivpp.ac.cn

Figures (4)
Tables (1)

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Fig. 1
Locality of the turtle egg fossil in the Laiyang Basin, Shandong Province.

A. sketch map of excavation sites in 2010 and 2011; B. the first excavation site showing the turtle egg position (the black circle).

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Fig. 2
stratigraphy showing dinosaurs, dinosaur eggs and turtle egg of the Laiyang Basin, Shandong Province (Modified from Wang et al. 2012Wang XL, Wang Q, Jiang SX, Cheng X, Zhang JL, Zhao ZK and Jiang YG. 2012. Dinosaur egg faunas of the Upper Cretaceous terrestrial red beds of China and their stratigraphical significance. J Stratig 36(2): 400-416.).

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Fig. 3
Holotype of Emydoolithus laiyangensis oogen. et oosp. nov.

A. the whole fossil specimen (IVPP V18544), showing the egg and a gastropod (in the white frame); B. top view of the egg, showing the interior filled by muddy siltstone; C. enlarged part of the egg (the white frame in A) showing small pieces of eggshell; D. the gastropod near the egg (the one in the white frame in A) Scale bars=1 cm.

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Fig. 4
Eggshell microstructure of Emydoolithus laiyangensis oogen. et oosp. nov.

A, radial section of eggshell (polarizing microscope); B - D, radial section of eggshell (SEM), C, enlarged lower part of the eggshell unit (SEM), showing aragonite ultrastructure, D, enlarged upper part of the eggshell unit (SEM), showing clear boundary of eggshell units; E - F, tangential section through the lower part of eggshell, E, showing tightly arranged eggshell units, F, enlarged part of E, showing crystal particles (white arrows) in eggshell units, Scale bars = 100 µm, u: eggshell unit, the white arrows indicating the boundary of eggshell units in C and D.

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TABLE I
Comparison of chelonian eggs described here and other rigid-shell fossil turtle eggs and turtle egg ootaxa, arranged in chronological order (modified from Jackson et al. 2008Jackson FD, Jin XS, Varricchio DJ, Azuma Y and Jiang YG. 2008. The first in situ turtle clutch from Cretaceous Tiantai Basin, Zhejiang Province, China. J Vert Pal 28: 319-325. ).

Ootaxon	Age	Location	Shell morphotype/egg shape	Egg size (mm)	Shell unit height-to-width ratio	Shell thickness (µm)	Shell units	References
Testudoolithus hirschi	Jurassic	Portugal	Rigid	?	1: 3	150	Parallel	Kohring (1999)Kohring R. 1999. Strukturen, biostratiomie, systematische und phylogenetische Relevanz von Eischalen amnioter Wirbeltier. Couier Forschungsinstitut Senckenberg 210: 1-307.
Unnamed	Early Cretaceous	Japan	Rigid/round or slightly elliptical	25 –27.5	8:5 –2:1^* * Calculate shell unit height-to-width ratio by the description of the reference (Isaji et al. 2006).	200 – 250 or 400 – 430	Parallel^* * Calculate shell unit height-to-width ratio by the description of the reference (Isaji et al. 2006).	Isaji et al. (2006)Isaji S, Matsushita A and Hirayama R. 2006. Chelonian eggshells from the Lower Cretaceous Kuwajima Formation of the Tetori Group, Central Japan. Paleont Res 10(1): 29-36.
Emydoolithus laiyangensis	Late Cretaceous	China	Rigid/elliptical	25 ×91	2:1 – 5:1	400 – 500	Parallel	This paper
Testudoolithus jiangi	Cretaceous	China	Rigid/round	42×45	2:1 – 5:2	500 – 700	Parallel	Fang et al. (2003)Fang XS, Lu LW, Jiang YG and Yang LF. 2003. Cretaceous fossil eggs from the Tiantai basin of Zhejiang, with a discussion on the extinction of dinosaurs. Geol Bull China 22(7): 512-520 (in Chinese)., Jackson et al. (2008)Jackson FD, Jin XS, Varricchio DJ, Azuma Y and Jiang YG. 2008. The first in situ turtle clutch from Cretaceous Tiantai Basin, Zhejiang Province, China. J Vert Pal 28: 319-325.
Testudinovum (egg containing embryo)	Cretaceous	Mongolia	Rigid/round	35×40	?	180(1991), 300 – 400 (1994)	Parallel	Mikhailov (1991Mikhailov KE. 1991. Classification of fossil eggshells of amniote vertebrates. Acta Palaeont Pol 36: 193-238., 1997)Mikhailov KE. 1997. Fossil and recent eggshell in amniotic vertebrates: fine structure comparative morphology and classification. Special Papers in Palaeontology 56: 1-80., Mikhailov et al. (1994)Mikhailov KE, Sabath K and Kurzanov S. 1994. Eggs and nests from the Cretaceous of Mongolia; p. 137-150 in Carpenter K, Hirsch KF and Horner JR (Eds), Dinosaur Eggs and Babies. Cambridge University Press, New York.
Unnamed (egg containing embryo)	Cretaceous	USA	Rigid/slightly elliptical	30×40	?	676	Slightly flared domed	Jackson et al. (2002)Jackson FD, Schweitzer MH and Schmitt JG. 2002. Dinosaur eggshell study using scanning electron microscopy. Scanning 24: 217-223.
Testudoolithus rigidus	Cretaceous-Pliocene	Various location	Rigid/round	42×47	2:1	220 –250	Parallel	Hirsch and Bray, (1988)Hirsch KF and Bray ES. 1988. Spheroidal eggs - avian and chelonian - from the Miocene and Oligocene of the western interior. Hunteria 1(4): 1-8., Hirsch (1996)Hirsch KF. 1996. Parataxonomic classification of fossil chelonian and gecko eggs. J Vert Pal 16: 752-762., Kohring (1999)Kohring R. 1999. Strukturen, biostratiomie, systematische und phylogenetische Relevanz von Eischalen amnioter Wirbeltier. Couier Forschungsinstitut Senckenberg 210: 1-307.
Haininchelys curiosa	Paleocene	Germany	Rigid/round	?	2:1	110 –240	Parallel	Schleich et al. (1988)Schleich HH, Kästle W and Dyck M Groessens-Van. 1988. Paläogene Eischalenreste von Hainin (Belgien). Palaont Zeitschrift 62: 133-146.
Testudinarum ovum	Paleocene Miocene	Germany	Rigid/round	?	2:1	50 –130	Parallel	Schleich and Kästle (1988)Schleich HH and Kästle W. 1988. Reptile Egg-shells SEM Atlas. Gustav-Fischer Verlag, Stuttgart, 128 p., Schleich et al. (1988)Schleich HH, Kästle W and Dyck M Groessens-Van. 1988. Paläogene Eischalenreste von Hainin (Belgien). Palaont Zeitschrift 62: 133-146.
Unnamed	Oligocene	USA	Rigid	43×47	?	?	?	Hay (1908)Hay OP. 1908. The fossil turtles of North America. Carnegie Institution of Washington 75: 1-568., Hirsch and Bray (1988)Hirsch KF and Bray ES. 1988. Spheroidal eggs - avian and chelonian - from the Miocene and Oligocene of the western interior. Hunteria 1(4): 1-8., Hirsch (1996)Hirsch KF. 1996. Parataxonomic classification of fossil chelonian and gecko eggs. J Vert Pal 16: 752-762.
Unnamed	Miocene	Venezuela	Rigid/elliptical	43.5×56.5	5:3	565 –730	Flared	Winkler and Sánchez-Villagra (2006)Winkler JD and Sánchez-Villagra MR. 2006. A nesting site and egg morphology of a Miocene turtle from Urumaco, Venezuela: evidence of marine adaptations in Pelomedusoides. Palaeontology 49: 641-646.

[1] Correspondence to: Xiaolin Wang, E-mail: wangxiaolin@ivpp.ac.cn

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New turtle egg fossil from the Upper Cretaceous of the Laiyang Basin, Shandong Province, China