An ancestral turtle from the Late Triassic of southwestern China

@article{Li2008AnAT,
  title={An ancestral turtle from the Late Triassic of southwestern China},
  author={Chun Li and Xiaocong Wu and Olivier Rieppel and Li-ting Wang and Li-jun Zhao},
  journal={Nature},
  year={2008},
  volume={456},
  pages={497-501}
}
The origin of the turtle body plan remains one of the great mysteries of reptile evolution. The anatomy of turtles is highly derived, which renders it difficult to establish the relationships of turtles with other groups of reptiles. The oldest known turtle, Proganochelys from the Late Triassic period of Germany, has a fully formed shell and offers no clue as to its origin. Here we describe a new 220-million-year-old turtle from China, somewhat older than Proganochelys, that documents an… 
The diapsid origin of turtles.
A Middle Triassic stem-turtle and the evolution of the turtle body plan
TLDR
A new reptile, Pappochelys, is reported that is structurally and chronologically intermediate between Eunotosaurus and Odontochelys and dates from the Middle Triassic period (∼240 million years ago), providing new evidence that the plastron partly formed through serial fusion of gastralia.
Evolutionary origin of the turtle skull
TLDR
High-resolution computed tomography and a novel character/taxon matrix are used to study the skull of Eunotosaurus africanus, a 260-million-year-old fossil reptile from the Karoo Basin of South Africa, whose distinctive postcranial skeleton shares many unique features with the shelled body plan of turtles.
Chinlechelys from the Upper Triassic of New Mexico, USA, and the origin of turtles
TLDR
The morphology of Chinlechelys tenertesta supports the placement of Testudines outside of crown Sauria, as a taxon derived from pareiasaurs based on the morphology of the dorsal osteoderms and skull roof and reaffirm its unequivocal support for the composite model of costal bone formation in turtles.
The origin of turtles: a paleontological perspective.
  • W. Joyce
  • Environmental Science
    Journal of experimental zoology. Part B, Molecular and developmental evolution
  • 2015
TLDR
The recently revived paleontological hypothesis that the Middle Permian Eunotosaurus africanus is an intermediate stem turtle is now robustly supported by numerous characters that were previously thought to be unique to turtles and that are now shown to have originated over the course of tens of millions of years unrelated to the origin of the turtle shell.
The early composition and evolution of the turtle shell (Reptilia, Testudinata)
The shell of the oldest true turtle (Testudinata) branch (Proterochersidae) from the Late Triassic (Norian) of Poland and Germany was built in its anterior and posterior part from an osteodermal
The Turtle Evolution: A Conundrum in Vertebrate Evo-Devo
TLDR
The stepwise, not necessarily saltatory, evolution of turtles is hypothesized, consistent with the recent finding of a transitional fossil animal, Odontochelys, that did not have the carapace but already possessed the plastron.
Microanatomy of the stem-turtle Pappochelys rosinae indicates a predominantly fossorial mode of life and clarifies early steps in the evolution of the shell
TLDR
Bone histological evidence reveals evolutionary changes in bone microstructure in ribs and gastralia approaching the turtle condition and evidence for a predominantly amphibious or fossorial mode of life in Pappochelys, which support the hypothesis that crucial steps in the evolution of the shell occurred in a terrestrial rather than fully aquatic environment.
...
...

References

SHOWING 1-10 OF 35 REFERENCES
The Origin of the Turtle Body Plan: Bridging a Famous Morphological Gap
TLDR
In pareiasaurs, the osteoderms represent the precursors of the chelonian shell and the morphology of the anterior region is consistent with the idea that the shoulder girdle in turtles has migrated posteriorly into the rib cage.
Phylogenetic Relationships of Mesozoic Turtles
TLDR
This revised topology has important implications for the evolution of several character complexes, because it implies that the common ancestor of all living turtles must have had a partially braced brain case and a primitive trochlear mechanism.
Owenetta and the origin of turtles
TLDR
New specimens of the small reptile Owenetta from the Upper Permian and Lower Triassic sediments of South Africa provide strong evidence that a group of primitive amniotes, the procolophonids, are the closest sister-group of turtles.
THE ORIGIN AND EARLY EVOLUTION OF TURTLES
TLDR
A critical reexamination of turtle relationships continues to support a sister-group relationship of turtles with a clade of marine reptiles, Sauropterygia, within crown-group Diapsida (Sauria), and an aquatic origin of turtles is suggested.
Correlated progression and the origin of turtles
TLDR
It is shown that certain pareiasaurs—dwarf, heavily armoured forms such a Nanoparia—approach the chelonian morphology even more closely than previously thought, suggesting that the rigid armoured body of turtles evolved gradually, through 'correlated progression'.
Morphogenesis of the turtle shell: the development of a novel structure in tetrapod evolution
TLDR
An anatomical investigations into plastron and carapace formation in the red‐eared slider, Trachemys scripta, and the snapping turtle, Chelydra serpentina suggest that the rib is organizing dermal ossification by secreting paracrine factors.
Palaeoecology of Triassic stem turtles sheds new light on turtle origins
  • W. Joyce, J. Gauthier
  • Environmental Science, Geography
    Proceedings of the Royal Society of London. Series B: Biological Sciences
  • 2004
TLDR
The palaeoecology of extinct turtles is investigated by first demonstrating that the forelimbs of extant turtles faithfully reflect habitat preferences, and it is found that although the common ancestor of all living turtles was aquatic, the earliest turtles clearly lived in a terrestrial environment.
Guanling Biota: A Marker of Triassic Biotic Recovery from the end‐Permian Extinction in the Ancient Guizhou Sea
TLDR
The Guanling Biota is of high diversity, containing well preserved and completely articulated skeletons of vertebrates comprising marine reptiles, fishes, and invertebrates including crinoids, ammonites, bivalves, and other fossils, and is one of the best examples of marine ecosystem records in life history.
Biology of turtles
TLDR
How the Turtle Gets Its Shell, S.F. Renous, F. de Lapparent de Broin, M. Davenport, and V. Bels Hindlimb Function in Turtle Locomotion: Limb Movements and Muscular Activation Across Taxa, Environment, and Ontogeny.
THE LATE TRIASSIC BLACK SHALES OF THE GUANLING AREA, GUIZHOU PROVINCE, SOUTH‐WEST CHINA: A UNIQUE MARINE REPTILE AND PELAGIC CRINOID FOSSIL LAGERSTÄTTE
Abstract:  Black shales of the lower member of the Carnian Xiaowa Formation (previously known as the Wayao Member of the Falang Formation or as the Wayao Formation) in the Guanling area, Guizhou
...
...