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Herpetology: the Biology of Tetrapods (BIOEE 470 and 472). • I’ll have the midterms graded and return them to you next Tuesday, as well as provide some grounds for optimism to anyone worried about their score on that first exam….
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• I’ll have the midterms graded and return them to you next Tuesday, as well as provide some grounds for optimism to anyone worried about their score on that first exam…
How many kinds of reptiles can you see in this vista at Wakulla Springs, FL?
Next reading assignment: Pough et al., Ch. 4, pp. 97-111 and pp.169-173
New vocabulary: carapace, plastron, bridge, scutes, osteoderm, Pleurodira, Cryptodira, Carettochelyidae, Ninjemys, Chelydridae, Cheloniidae, Dermochelyidae, Emydidae, Terrapene, Testudinidae, Gopherus, Trionychidae, Kinosternidae, Alligatoridae, Crocodylidae, Gavialidae, thecodont
••Turtles: controversial relationships and origin
••Archosaurs: crocs, pterosaurs, dinosaurs including birds
••Lepidosaurs: tuatara, “lizards,” amphisbaenians, snakes
• Ectothermic (except for birds) with scaly epidermis (elaborated as feathers in birds), but otherwise differences are impressive!
• These are ancient lineages and traditionally “reptiles,” including “mammal-like reptiles” (=stem mammals or basal synapsids), were the “taxonomic dregs” after mammals and birds had been elevated to special status among amniotes…
• Turtle, tortoise, terrapin, chelonian
• Shell is a box of dermal bone, encompassing ribs, spine, girdles; consists of carapace, plastron, and bridge
• Beak, no teeth (occur in stem turtles)
• Longitudinal vent, penis, eggs, TDSD
• Lungs are boxed in, expand at base of limbs, pharyngeal and buccal pumping, cloaca sometimes functions as a gill
• Aquatic ancestor, preoccupied feeding
Upper: Heosemys, Vietnam;
middle: Chelus, South America;
bottom: Claudius, Mexico
• Two clades: Pleurodira and Cryptodira
• Pleurodira or “side-necked” turtles, in which the head retracts in and S-bend to the right or left
• Southern continents, relicts from Gondwanaland (see maps in Pough et al.)
• Modest diversity of species and shell form: mostly pond turtles, river turtles, or bottom walkers
• Stupendemys, 2.3 m shell!
Upper left and right: Phrynops; bottom Hydromedus; both Brazil
(bottom (photo:M.Martins; others H.W.Greene)
• “Hidden-necked” turtles, in which the head retracts in a vertical S-bend, are cosmopolitan, mostly on northern continents (maps in text)
• Cryptodirans exhibit great diversity of species, shell form, and ecology—Trachemys scripta is probably the most widely distributed turtle!
• Horned Meiolanidae, recently extinct sister taxon of cryptodires, survived until Late Pleistocene on islands off Australia
• Ninjemys: “Ninja, in allusion to those totally rad, fearsome foursome who epitomize shelled success; emys, turtle”
(E.H.Gaffney, 1996, Bulletin of the American Museum of Natural History 229:1-166)
bottom from P.V.Rich et al., Kadimakara: Extinct Vertebrates of Australia)
• Are there really just five “kinds” of turtles? Compare these convenience categories with photos and descriptions in text... Are all of them found in NY?
• First, slow-moving “bottom walkers”: tough carapace, small plastron, probably primitive; includes many pleurodires, Chelydra, and Kinosternidae —these are the epitome of “preoccupied foraging,” and they are generally well-defended…
Chelydra serpentina, NY
(Upper photo:H.E.Evans; lower:D.Steen)
• Second, “pond turtles” (e.g., Emydidae): hydrodynamic baskers, such as our local Chrysemys picta—one of the world’s most beautiful animals!
• Third, “soft-shelled turtles” (Carettochelyidae and Tryonichidae): fast-moving and sneakey hunters, flat and smooth, long neck and snout
Upper: Pseudemys, FL;
lower: Carettochelys, New Guinea
• Fourth, “sea turtles” (Cheloniidae and Dermochelyidae): fused digits, totally marine, weird diets
• Females return to natal beach to nest, later there is a “hatchling frenzy”—otherwise marine turtles never leave the sea…
• Leatherback is heaviest living reptile, eats jellyfish and thus also plastic bags, seriously endangered…
Upper and middle: Chelonia mydas;
lower: Dermochelys coriacia; both Costa Rica
(lower photo:W.E.Rainey; others:V.Perez)
• Fifth, “tortoises” have a hard domed shell and elephantine feet, are terrestrial, and are at least partly or totally herbivorous
• Testudinids—true tortoises —are cosmopolitan and always herbivorous
• Tortoises are good to eat, easy to catch, and often endangered
Upper: Geochelone, Galapagos Islands;
bottom: Gopherus polyphemus, FL
• One, herbivory: strict vegetarians, large gut, high through-put
• Two, omnivory (widespread): often more specialized as insectivorous juveniles and herbivorous adults (Trachemys scripta)
• Three, carnivory: eat animals, including vertebrates
••pluckers that snap, crush, shear (Kinosternidae)
••spearers like Apalone, Chelydra
• Four, neustophagia: eat neuston, “wine glass” analog (various pond turtles, e.g., some pleurodires and emydids)
• Not necessarily congruent with my “five kinds of turtles” scheme…
• Gopher Tortoise (G. polyphemus), southeastern US; Texas Tortoise (G. berlandieri), south TX and northern Mexico; Desert Tortoise (G. agassizii), southewestern US and northwestern Mexico; and Bolson Tortoise (G. flavomarginatus), north-central Mexico
• All dig burrows, and they often have special conservation status
• Bolson Tortoise, described as a new species in 1958, reaches 50 kg (100 lbs), is endangered and a candidate for Pleistocene rewilding
(from H. Vetter, 2004,
Turtles of the World, Vol. 2)
• Desert Tortoise: found in Mohave and Sonoran Deserts of AZ, CA, UT, and northwestern Mexico
• Some populations endangered by persecution and landscape changes
• Ecological community roles as engineers, commensals, seed dispersers, etc.
• Sex, death, and education in the Mohave Desert…
• Human garbage led to more Ravens, and more Raven predation on young Desert Tortoises
• Off-road vehicle traffic crushes tortoises and their burrows, and their riders sometimes even shoot tortoises…
Desert Tortoise Preserve, California City, CA
• North American box turtles are specialized terrestrial emydids; they evolved from a pond turtle heritage
• Emydids that are somewhat convergent on tortoises—in what ways, ecologically and moprhologically?
• Terrestrial and omnivorous, but T. coahuilae is secondarily aquatic (we will see it at the Bronx Zoo)
• Great book by Ken Dodd!
• Complex and unexpected behavior
••Clemmys insculpta and how it finds worms to eat
••Parental care in Kinosternon and Gopherus
••Predatory behavior of Philadelphia Geochelone
• They are vulnerable and threatened for food and pet trade (ironic, given so well protected in nature)
• Bog Turtles (Clemmys muhlenburgi) exemplify several conservation issues…
Bog Turtle hatching at Zoo Atlanta