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The scute effectively forms the skin over the underlying bony structures; there is a very thin layer of subcutaneous tissue between the scute and the skeleton. The scutes can be brightly colored in some species, and turtle shells often follow Thayer's law with carapace usually being a darker patterning than the plastron, [ 25 ] though there are ...
The term "gastralia" was proposed by Georg Baur in 1898. [6] They had previously been termed "abdominal ribs", [7] but because the term "abdominal ribs" has been applied to various structures, and the gastralia are not true ribs, this is not considered an appopriate term.
Chelids also lack mesoplastra, which separates them from the Pelomedusidae. The cervical scute is usually present, though it is absent in some species of Elseya and Myuchelys. Otherwise, the carapace has the usual complement of four costals, five vertebrals and twelve marginals (per side).
The bones of the postcranial skeleton are thick, having undergone pachyostosis. Mesosaurus is unusual among reptiles in that it possesses a cleithrum, usually found in more primitive bony fish and tetrapods. [13] The head of the interclavicle of Mesosaurus is triangular, unlike those of other early reptiles, which are diamond-shaped. [14]
They found that the musculature of the forelimbs was conservative, particularly compared to those of early bipedal saurischian dinosaurs, but the pelvic and hindlimb musculature was instead more derived (or "advanced"), due to peculiarities of the skeleton. These areas had large muscles, and combined with the wide pelvis and stout hind limbs ...
The Pleurodira are one of the two living suborders of turtles, the other being the Cryptodira.The division between these two suborders represents a very deep evolutionary divide between two very different types of turtles.
Most osteostracans had a massive cephalothorac shield, but all Middle and Late Devonian species appear to have had a reduced, thinner, and often micromeric dermal skeleton. This reduction may have occurred at least three times independently because the pattern of reduction is different in each taxon. [ 4 ]
Officers at Fort Wallace, Kansas, in 1867.Theophilus H. Turner, who the same year discovered Elasmosaurus in the area, is second from left.. In early 1867, the American army surgeon Theophilus Hunt Turner and the army scout William Comstock explored the rocks around Fort Wallace, Kansas, where they were stationed during the construction of the Union Pacific Railroad.