ONLY EXTANT ANAPSIDS- TURTLES- Sister group to ---Diapsids?- Lepidosaurs?TURTLES LACK TEETH- jaws are surrounded by a hard keratinous sheath – the Ptomium- Ptomium has sharp edge – cut both plant & animal foodClassified by the way that they bend their neck backwards2 Major GroupsCryptodira – Largest group- all my favorite turtles1. 10 families2. worldwide3. Retract Head by Bending neck in a vertical s-shape4. So-called “s-necked” turtlesPleurodira – snaked necked turtles, bum breathing turtles & the matamata1. 3 families2. only in southern hemisphere3. Rectract Head by bending neck Horizontally (to the side)4. So-called “sided necked turtles”TURTLE SHELLthe shell is composed of two layers, an outer layer (epidermis) and an innerlayer, and that the inner layer is derived from elements of both the endoskeleton andexoskeleton• Dermal bones (part of the inner layer - derived from the exoskeleton)• Endochondral bones (part of the inner layer - derived from the endoskeleton)The Testudine shell elements1. Endoskeletona. Vertebral columnb. Ribsc. Clavicald. interclavical2. Dermoskeletona. Plates of dermal bones3. Epidermisa. Keratinous scutesTwo halves of turtle shell1. Carapace (upper)2. Plastron (lower)Groups with modified shell – Hinged Shells1. Box Turtles (Emydidae)a. Hinge b/w hyoplastral & hypoplastral bones allows the plastron to close openings of shell2. Mud Turtles(Kinosternidae)a. Double hinge, 1 anterior (b/w epiplastra & entoplastron) & one posterior(b/w the hypoplastron & xiphiplastron)-Shell Loss1. Soft shelled (Trionychidae)Lack keratinous scutes & the bony plates are greatly reduced3. Leatherback (Dermochelyidae)Lack keratinous scutes & the typical dermal bone plates are replaced by thousands of tiny dermal bonesINSIDE THE SHELL- The ribs fuse (during development) to the costal series of bony plates which provides further reinforcement for the shell- Pectoral girdle is inside the rib cageEVOLVINLATE TRIASSIC-earliest known is Odontochelys (stem-group testudinan) lacked carapace but had a plastron-Second oldest – Proganochelys – identical to modern turtle- no known intermediatesCostal Ventilation not possible in turtles – Ribs fused w/ shells-hold breath in shellsea turtles cant breathe while walk, but some catBox turtle gait is diagonal forelimb movement counteracts hind linbChallenges with this mode of lung ventilation READ BOOK pages 314-315.ALTERNATIVE RESPIRATORY SURFACESRHOEDYTES LEUKOPS – the butt breather-uses its highly vascularized Cloaca as a respiratory surface-hold cloacal orifice open & rapidly pumps water in & out @ a rate of 15-60X per minute -----CLOACAL RESPIRATION--helps that they live in cool fast flowing oxygen rich streams-other aquatic turtles (includes softshells) use pharynx as an additional respiratory surface under