. Chordate morphology. Morphology (Animals); Chordata. clemys temminckt, the Alligator Snapping Turtle; Chelydra ser- pentina, the Snapping Turtle; and Terrapene Carolina, the Box Turtle. The solid roof may be emarginated posteriorly (Figure 4-9). In Terrapene it is largely missing, except for a lateral squamosai-postorbital arch. The parietal forms a part of the endocranial wall, extending down in front of the trigeminal nerve to contact the palatoquadrate (pterygoid)—the Vi branch passes medial to this process, which lies in the posi- tion of the lizard epipterygoid. There has been extensive
. Chordate morphology. Morphology (Animals); Chordata. clemys temminckt, the Alligator Snapping Turtle; Chelydra ser- pentina, the Snapping Turtle; and Terrapene Carolina, the Box Turtle. The solid roof may be emarginated posteriorly (Figure 4-9). In Terrapene it is largely missing, except for a lateral squamosai-postorbital arch. The parietal forms a part of the endocranial wall, extending down in front of the trigeminal nerve to contact the palatoquadrate (pterygoid)—the Vi branch passes medial to this process, which lies in the posi- tion of the lizard epipterygoid. There has been extensive loss of bones in this type of skull: the lacrimal, postfrontal, su- pratemporal, postparietal, septomaxilla, and splenial are lacking. The nasal, ectopterygoid, and epipterygoid are usually lacking; the epipterygoid is at best rudimentary and the ectopterygoid may never be present. The parasphenoid is lacking or much reduced. Other peculiarities are as follows: the vomers fuse medially and suture with the pterygoids; the posterior margin of the quadrate is deeply incised or encloses the shaft of the stapes; and the jaw margins are toothless and covered by a horny sheath. The hyoid apparatus consists of a plate-like copula to which are attached hyoid cornua (horns) and ceratobran- chial I and II processes. The development of this type of head skeleton shows a few- modifications. No bones other than those observed in the adult are evident during developmental stages. The vomer develops from bilateral centers but these soon fuse. Two parasphenoid centers appear in the sea turtle, Lepidochelys, but disappear as the pterygoids meet below the basi- sphenoid, obliterating the basipterygoid processes and closely investing most of the basisphenoid. An anterior process of the supraoccipital is present. The head skeleton of the turtle appears to be modified in almost every respect. Further evidence of the simplifica- tion (or inherent simplicity) of this type is the lack of a pouched J
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Keywords: ., bo, bookcentury1900, bookcollectionbiodiversity, bookleafnumber87
