gel_lec_12

gel_lec_12 - Lecture 12 – 2/8/10 “Triassic Takeover”:...

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Unformatted text preview: Lecture 12 – 2/8/10 “Triassic Takeover”: turnover of the vertebrate fauna on land that took place during the Triassic How did sauropsids evolve in the Paleozoic? • Carboniferous-Permian Sauropsids - Par ar e p til e s (s o m e bi g, o u t n u m b e r e d): pr o c olo p h o n – d o e s n’t h a v e c h e e k o p e ni n g, m o s t like h e r bivor e, s c u t o s a u r u s - Dia p si d s: p e tr ol a c o s a ur u s – firs t di a p si d, lat e c a r b o nif ero u s , c h e e k o p e ni n g, h o v a s a u r u s, w ei g eltis a u rid a e • S a ur o p si d s di d n o t b e c o m e d o mi n a n t; lar g e h e r bivor e s e v olv e d b u t n o t m a n y; w orld w a s c o d ry, n o rigoro u s t h e r m or e g ul a tio n • Sy n a p si d s b e c a m e d o mi n a n t, e v olu tio n of lar g e h e r biv or e s Wh a t is t h e “Tria s sic Take ov e r ”? • Wh a t u s e d t o b e s y n a p si d w orld t ur n e d int o di a p si d • E.G. c ar nivor e: Her bivor e: dicy n o d o n t (sy n a p si d) > rhy n c h o s a u r (di a p s d) > pr o s a ur o p o d di n o s a u r (di a p si d) Wh er e d o h e r bivoro u s pl a y e r s b elo n g in t h e fa mily tr e e of v e r t e b r a t e s ? Lepido s a u r • S p h e n o d o n: in Ne w Z e al a n d o nly; e x tin c t el s e w h e r e; h a v e n o t c h a n g e d m u c h si n c e d i n o s a u r s; NZ di d n o t h a v e m a n y m a m m ali a n pr e d a t or s; n o c t ur n al, h a v e t w o o p e ni n g s, d o n r e pl a c e t h eir t e e t h • S q u a m a t a (liz ar d s, s n a k e s): p a r a p h yl e tic g r o u p Wh er e d o c a r nivoro u s pl a y e r s b elo n g in t h e fa mily tr e e of v e r t e b r a t e s ? Arc ho s a u r s (croc o dil e s a n d di n o s a u r s) (On firs t s t e m , b ef or e croc o dil e s) • Rhy n c h o s a u r s: mi d dl e Tria s sic; h a v e c h u n k of b o n e w h e r e t e e t h c o m e u p c o n s t a n tly, p r ovidin g grin di n g s e r vic e; h a d a d v a n t a g e for e a ti n g s o m e t hi n g r e ally h a r d • Tanys tro p h e u s : e a rly t o la t e Trais sic; “t a n y” – el o n g a t e d , “ s tr o p h e u s ” – v e r t e b r a e ; h a d b o n e s in n e c k; n e c k u s u. b e n t in fo s sils • Me g al a n c o s a ur u s: lat e Trais sic; fro m It aly, Switz e rl a n d; tr e e-cli m b e r, ins e c tivor e (croc o dile b r a n c h) • O r nit h o s u c h u s: la t e Tria s sic • Ticino s u c h u s: m i d dl e t o la t e Trais sic; d o g-like Croc o dil e s: t hi g h b o n e g o e s s t r ai g h t u p t o hi p Dino s a ur: t hi g h b o n e g o e s si d e w a y s int o hi p • Prot o s u c h u s: la s t of d o g lookin g cr o c o dil e s; sk ull is flat wit h pit s o n t o p (lik e t o d a y’s cr o c) Lost tr a ck of cr oc s, n e x t ti m e w e s e e t h e m , t h e y’r e in w a t e r ( e a rly Jur a s sic – lat e cr e t a c e o u s • Cr e t a c e o u s cr oc o dil e s b e c a m e lar g e (s arc o s u c h u s c o uld b e 1 0 m or m o r e ); c old-blo o d e d • Three lineages of crocodile today (dinosaur branch) • Scleromoclus: late Triassic • Pterosaurs: flying reptiles, late Jurassic; had long tail but lost it; first active flyers like birds What were the causes of takeover? • Climate was changing • Ice house during Permian, transfor med to green house in Triassic • Had no need to spend extra energy to ther moregulate Permian/Triassic: cycads, ginkos, glossopterids, cordaites Late Triassic: conifers • Crocodiles and dinosaurs have erect postures • Carrier’s constraint – synapsids were half­erect (problem: one side of lung always compress cannot function opti mally) ...
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