Correlated progression and the origin of turtles

  title={Correlated progression and the origin of turtles},
  author={Michael S. Y. Lee},
TURTLES exhibit some of the most extreme postcranial modifications found in vertebrates. The dorsal vertebrae and ribs have fused with dermal armour, forming a totally rigid box-like trunk region1,2 Our understanding of chelonian origins has been restricted by a paucity of information on intermediate forms3,4, however, and it is often assumed that they must have evolved saltationally5. It has been suggested that pareiasaurs, a group of large herbivorous anapsid reptiles, are the sister-group of… 

The endoskeletal origin of the turtle carapace

This work examines turtle embryos and finds that the costal and neural plates develop not within the dermis, but within deeper connective tissue where the rib and intercostal muscle anlagen develop.

Patterns of morphological evolution in the skull of turtles: contributions from digital paleontology, neuroanatomy and biomechanics

Using 3-D models and ancestral state reconstructions, the arrangement and gross morphology of the jaw adductor musculature in Proganochelys quenstendti, the earliest turtle with a complete shell, is inferred, an important step towards the understanding of the evolution of those muscles in turtles.


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.

A thin-shelled reptile from the Late Triassic of North America and the origin of the turtle shell

The novel observations of Chinlechelys tenertesta lend support to the hypothesis that the turtle shell was originally a complex composite in which dermal armour fused with the endoskeletal ribs and vertebrae of an ancestral lineage instead of forming de novo.

An ancestral turtle from the Late Triassic of southwestern China

A new 220-million-year-old turtle from China is described that documents an intermediate step in the evolution of the shell and associated structures and shows that the turtle shell is not derived from a fusion of osteoderms.

Morphogenetic and constructional differences of the carapace of aquatic and terrestrial turtles and their evolutionary significance

Differences in the structure of the bony shell in aquatic and terrestrial turtles were shown to be associated with varying degrees of development of epidermal derivatives, namely, the thickness of the scutes and the depth of horny furrows.

Evolution of the Turtle Body Plan by the Folding and Creation of New Muscle Connections

This work proposes that the evolutionary origin of the turtle body plan results from heterotopy based on folding and novel connectivities, and suggests that some limb muscles establish new turtle-specific attachments associated with carapace formation.

Body plan of turtles: an anatomical, developmental and evolutionary perspective

Comparative developmental data allow us to hypothesize the gradual evolution of turtles, which is consistent with the recent finding of a transitional fossil animal, Odontochelys, which did not have the carapace but already possessed the plastron.

Nature of the turtle shell: Morphogenetic causes of bone variability and its evolutionary implication

Variations in the bony shell structure are observed in (1) unusual shape and size of plates combined with normal number of plates, (2) presence of additional plates, and (3) absence of regular plates.

The Origin and Early Evolution of Turtles Author ( s ) :

■ Abstract 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



The Development and Evolution of the Turtle Body Plan: Inferring Intrinsic Aspects of the Evolutionary Process from Experimental Embryology

Surgical perturbations were designed to test the causal connection between the epithelial-mesenchymal interaction in the body wall and the unusual placement of the ribs in turtles.

Historical Burden In Systematics And The Interrelationships Of ‘Parareptiles’

Turtles are the highly modified survivors of a radiation of poorly‐known reptiles commonly called ‘parareptiles’, and the procolophonoid hypotheses is supported by only one synapomorphy (the slender stapes).

A Survey of Adaptive Relationships of Dentition to Diet in the North American Iguanidae

The chief aim of this comparison is to determine, in general, whether lizard dentition shows adaptive response to selective factors operating through diet, or whether its evolution is so intimately related to that of other characters not directly influenced by diet, that the effect of diet on dentition cannot be discerned.

The Evolution of Terrestrial Locomotion

Nearly all workers in this field have agreed that the tetrapod limb evolved as a locomotor organ which allowed movement away from the pond or swamp habitat of the rhipidistians and onto the land.

Studies on skeleton formation in reptiles: Patterns of ossification in the skeleton of Chelydra serpentina (Reptilia, Testudines)

Convergence of ontogenetic repatterning in the ossification of the axial skeleton in Chelydra and Squamata is discussed, as are problems of adaptive modification of oSSification patterns.

A reevaluation of early amniote phylogeny

It is indicated that three major clades of amniotes extend from the present to the Palaeozoic, and these three clades are the Synapsida (including Mammalia), Parareptilia (including Testudines), and Eureptili (including Sauria).

Late Triassic Turtles from South America

It is proposed that Australochelidae is the sister group of Proterochersis plus Casichelydia, that turtles were diverse by the Late Triassic, and that Casicheydia probably originated during the Jurassic.

Biology of the Reptilia

  • C. Gans
  • Biology, Environmental Science
  • 1969
Why Study Reptilian Development? The Origin and Development of Oocytes Embryology of Turtles Embryology of Marine Turtles Development of Crocodilians Embryology of the Tuatara Some Developmental

Exaptation—a Missing Term in the Science of Form

This work presents several examples of exaptation, indicating where a failure to conceptualize such an idea limited the range of hypotheses previously available, and proposes a terminological solution to the problem of preadaptation.

Vertebrate Paleontology and Evolution

"Carroll has to his credit an immense amount of useful labour in writing the book and will probably corner the market for a vertebrate paleontology text for the rest of this century." Nature