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Biogeography of CrocodYlians Joyce Ann Boutilier

Biogeography of CrocodYlians Joyce Ann Boutilier Distribution Crocodiles Caimans Phylogeny Evolution Alligators Gharials From the beginning… Some background… Crocodylian ancestors first arose during the Mesozoic Era Mesozoic Era = ~ 251 mya to 65 mya Anapsid Diapsid

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Biogeography of CrocodYlians Joyce Ann Boutilier

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  1. Biogeography of CrocodYliansJoyce Ann Boutilier

  2. Distribution Crocodiles Caimans Phylogeny Evolution Alligators Gharials

  3. From the beginning…

  4. Some background… • Crocodylian ancestors first arose during the Mesozoic Era • Mesozoic Era = ~ 251 mya to 65 mya Anapsid Diapsid TRIASSIC 200 million years ago JURASSIC 135 million years ago CRETACEOUS 65 million years ago

  5. Ancient Distribution ?

  6. SUPERCROC

  7. The Crocodylian Body Plan… • Very successful body plan • Eyes and nose on top of skull • Semi-erect posture • All four resemble each other • However, some differences: • salt excreting organs • snout shape

  8. Evolution Controversy Traditional Hypothesis Haemothermia Hypothesis

  9. The families: Classification • Order Crocodylia • Superfamily Gavialoidea • Family Gavialidae - Gharials • Superfamily Alligatoridea • Family Alligatoridae • Subfamily Diplocynodontinae (extinct) • Subfamily Alligatorinae- Alligators • Subfamily Caimaninae- Caimans • Superfamily Crocodyloidea • Family Crocodylidae • Subfamily Mekosuchinae (extinct) • Subfamily Crocodylinae - Crocodiles

  10. Let’s meet the families… Alligatoridae Crocodylidae Gavialidae From the top: American alligator (Alligator mississippiensis), Nile crocodile (Crocodylus niloticus), Indian gharial (Gavialis gangeticus)

  11. Family Alligatoridae American alligator (Alligator mississippiensis) Chinese alligator (Alligator sinesis)

  12. Alligatoridae Paleosuchus palpebrosus Paleosuchus trigonatus Caiman yacare Caiman crocodilus apaporiensis Melanosuchus niger Caiman crocodilus Caiman latirostris Caiman crocodilus fuscus

  13. Crocodylidae C. acutus C. moreletii C. cataphractus C. intermedius C. siamensis C. johnstoni C. mindorensis Osteolaemus tetraspis C. rhombifer C. niloticus C.novaeguineae C. palustris Crocodylus porosus

  14. Which is which?? • Shape of the jaw • V-shaped, pointy snouts versus U-shaped, round snouts • Teeth • Fourth tooth showing versus covered up when closed • Habitat • Special glands in their tongues work well versus not well means saltwater habitats versus freshwater habitats. CROCODILE ALLIGATOR

  15. Gharials Family Gavialidae Actually Crocodylidae!! Gavialis gangeticus Indian Gharial Tomistoma schlegelii False Gharial

  16. Gavialidae Controversy • Schematic view of crocodilian • Relationships based on • morphological and • (B) molecular data

  17. HatchlingAdult

  18. Modern Crocodylian World Wide Distribution

  19. Modern Crocodylians: Number of Species per Country Note: this does not show the actual geographic distribution of crocodilians.

  20. Alligatoridae Distribution Alligator and Caiman Range: southern United States and eastern China; caimans are found in Central America and South America American Alligator (Alligator mississippiensis)

  21. Alligatoridae Distribution China: restricted to areas Around the lower Yangzi River Chinese alligator (Alligator sinensis)

  22. Alligatoridae Distribution Spectacled caiman (Caiman crocodilus ) Caiman Range: Central America and South America Brazil, Colombia, Costa Rica, Cuba, Ecuador, El Salvador, French Guiana, Guatemala, Honduras, Mexico, Nicaragua, Panama, Peru, Puerto Rico, Surinam, Tobago, Trinidad, United States, Venezuela

  23. Crocodylidae Distribution Crocodile Range: Mexico, Central and South America, Africa, Southeast Asia, and Australia American Crocodile (Crocodylus acutus)

  24. Gavialidae Distribution Historical range of gharials: India, Pakistan, and Nepal. Numbers very low or extinct in Bangladesh, Bhutan, and Burma. Not an accurate representation of present distribution, which is more restricted now.

  25. ClimateLimitations

  26. Conservation

  27. Implications to Humans

  28. Why did they outlive the dinosaurs?

  29. Bad Conditions?

  30. YIKES!

  31. Questions?

  32. CLASS REPTILIA ORDER CROCODYLIA • FAMILY ALLIGATORIDAE • Genus Alligator • Alligator mississippiensis • Alligator sinesis • Genus Caiman • Caiman crocodilus • Caiman latirostris • Caiman yacare • Genus Melanosuchus • Melanosuchus niger • Genus Paleosuchus • Paleosuchus palpebrosus • Paleosuchus trigonatus • FAMILY GAVIALIDAE • Genus Gavialis • Gavialis gangeticus • FAMILY CROCODYLIDAE • Subfamily Crocodylinae • Genus Crocodylus • Crocodylus acutus Crocodylus cataphractus Crocodylus intermedius Crocodylus johnstoni Crocodylus mindorensis Crocodylus moreletii Crocodylus niloticus Crocodylus novaeguineae Crocodylus palustris Crocodylus porosus Crocodylus rhombifer Crocodylus siamensis Osteolamus tetraspis • Subfamily Tomistominae • Genus Tomistoma • Tomistoma schlegelii

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