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Crocodylians-diapsid skullsOviparous; internal
fertilizationSemi-aquatic; bask on
shorelines-12-60 eggs per clutchnest in mounds of vegetation
mostlyadapted well to an aquatic
niche
ProposedCrocodylian Phylogenies
Newest crocodylian phylogeny – Roos et al. (2007)Molecular Phylogenetics and Evolution 45: 663–673
Character Family Alligatoridae Family Crocodilidae Family Gavialidae
Popular Name Alligators and Caimans True crocodiles Gharial
Head & Snout More oval than triangular Broad, triangular head with a short Snout Beak-like extension of the snout
4th lower tooth (when the mouth is closed) Not visible from outside Visible from outside Visible from outside
Mandibular Symphysis (joint between two halves of lower jaw)
Extends to a level less than 23rd tooth
Extends to a level less than23rd tooth Extends to a level of 23rd or 24th tooth
Distribution S. America, China, USA Asia, Africa, Australia & Pacific Islands & USA Asia (India & Nepal)
No. of Genera (No. of species given in brackets)
Alligator(2) Caiman(2) Paleosuchus(1) Melanosuchus(2)
Crocodylus (11) Osteolaemus(1) Tomistoma(1) Gaviali
Family GavialidaeGharials
monotypicGavialis gangeticus-SW Asian River Basins
longest and narrowest jaws of all crocodylians
-males grow a boss on snout tip-most aquatic of crocodylians-impale fish by swiftly moving head-4 m in length(not really dangerous to man)
Family AlligatoridaeSubfamily Alligatorinae2 speciesAlligator mississippiensis
American AlligatorSE USA4 metersopportunistic carnivorebreed at 2.1 meters in lengthyoung have a very different
colorationAR Post National Memorialfemales show parental care
A. sinensisChinese Alligator2.1 meters40% of diet is molluskshibernatessimilar reproduction to Americanlower jaw fits within mouth upon
closure
Subfamily Caimaninae3 genera; 7 species-Central to south America, Amazonia-small to large 1.7m to 5m-freshwater-mound nest builders-harvested and habitat destructionCaiman crocodilus
introduced into south FL.interaction with FL crocs?
Dwarf Caiman (Paleosuchus)
Family CrocodylidaeCrocodiles and False Gharials2 subfamilies pan - tropicalmoderately long and broad jawswhen mouth is shut,
fourth mandibular tooth is exterior
Subfamily Crocodylinae2 genera; 14 species Crocodylus acutus
-American crocodile-up to 15 ft.-habitat destruction, moving into salt water-400 left in Everglades
C. porosus-Estuarine crocodile-up to 20 feet-often seen at sea-opportunistic predator
C. niloticus-Nile Crocodile-16 feet-quite dangerous, heavily populated Nile Valley-perhaps 5,000 people a year could be eaten-can build a sand nest but prefers mounds
OsteolaemusDwarf crocodile exclusively nocturnal
Subfamily TomistominaeFalse Gharial
monotypicTomistoma schlegelii
-Borneo and Sumatra, Malay Peninsula-fish eater like gharial, can also ambushpoorly known, overhunted, habitat destruction