INTEGBI 175LF Lecture Notes - Lecture 16: Gastralium, Posterior Nasal Apertures, Aorta
14 May 2018
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Lecture 16: CROCODILIANS
●Archosaurs : more closely related to birds than other reptiles
●Range: every continent but Europe
●Not sp.-rich, but are top predators
●Characteristics:
○Osteoderms : form armor w/in skin
○Aquatic adaptations:
■Paddle tail w/ double row of dorsal keels
■Webbed hands and feet
■Transparent membrane on eye
■Fold of skin w/ osteo covers tymp during dives
■Eyes and nostrils dorsally placed
■Nostrils valved
■Secondary palate : sep oral cavity from resp and esophagus
■Internal nares (choanae) : sealed of by palatal valve
○Cardiovascular system:
■Unidirectional lung ventilation
■Diaphragmatus muscle : originates on girdle, attached to liver
■Inspiration: contraction of diaphragm and ischiopubis muscle , pull liver/lungs
posteriorly, lungs expand
■Expiration: contraction of rectus and transversus abdominis pulls pubes and
gastralia, pushes liver forward, compresses lungs → liver acts as plunger/piston
■4-chambered heart w/ unique shunting during dives:
●Pressure greater in L than R
●Blood lows thru foramen panizzae and holds R bicuspid semilunar
valve closed
●O2 deficient blood directed to lungs and O2 rich directed to systemic
and head from R aorta
●When diving, pressure in L/R ventricles equalizes → blood lows from R
ventricle to L aorta allowing mixing
○No reason for blood to lungs while diving
○Induced hypometabolic state , incr duration
●Specialized hemoglobin - more O2 than any other vertebrate
●Tolerate lactic acid buildup to pH = 6.1
●Can submerge for 2+ hr
○Feeding:
■Stealth predators, drown large prey
■No mastication → dismember w/ death roll , may let food rot
■Pyloric gizzard : grinds food, lithophagy, stones 1-5% BW
■Pterygoideus muscle : large for jaw closure
■Weak jaw abduction
■Fish feeders have long, slender snouts
○Communication:
Document Summary
Ar(cid:283)hosaurs : mo(cid:418)e (cid:283)losel(cid:482) (cid:418)elated to (cid:282)i(cid:418)ds than othe(cid:418) (cid:418)eptiles. Paddle tail (cid:476)/ dou(cid:282)le (cid:418)o(cid:476) o(cid:321) dorsal keels. Fold o(cid:321) skin (cid:476)/ osteo (cid:283)o(cid:475)e(cid:418)s t(cid:482)mp du(cid:418)in(cid:322) di(cid:475)es. Se(cid:283)ondary palate : sep o(cid:418)al (cid:283)a(cid:475)it(cid:482) (cid:321)(cid:418)om (cid:418)esp and esopha(cid:322)us. Internal nares (cid:1827)(cid:283)hoanae(cid:1828) : sealed o(cid:498)(cid:321) (cid:282)(cid:482) palatal (cid:475)al(cid:475)e. Diaphra(cid:322)matus mus(cid:283)le : o(cid:418)i(cid:322)inates on (cid:322)i(cid:418)dle, atta(cid:283)hed to li(cid:475)e(cid:418) Inspi(cid:418)ation: (cid:283)ont(cid:418)a(cid:283)tion o(cid:321) diaph(cid:418)a(cid:322)m and is(cid:283)hiopu(cid:282)is mus(cid:283)le , pull li(cid:475)e(cid:418)/lun(cid:322)s poste(cid:418)io(cid:418)l(cid:482), lun(cid:322)s e(cid:481)pand. E(cid:481)pi(cid:418)ation: (cid:283)ont(cid:418)a(cid:283)tion o(cid:321) re(cid:283)tus and trans(cid:475)ersus a(cid:282)dominis pulls pu(cid:282)es and (cid:322)ast(cid:418)alia, pushes li(cid:475)e(cid:418) (cid:321)o(cid:418)(cid:476)a(cid:418)d, (cid:283)omp(cid:418)esses lun(cid:322)s li(cid:475)e(cid:418) a(cid:283)ts as plun(cid:322)e(cid:418)/piston. 4-(cid:283)ham(cid:282)ered heart (cid:476)/ uni(cid:417)ue shuntin(cid:322) du(cid:418)in(cid:322) di(cid:475)es: Blood (cid:500)lo(cid:476)s th(cid:418)u (cid:321)oramen panizzae and holds r (cid:282)i(cid:283)uspid semilunar (cid:475)al(cid:475)e (cid:283)losed. O(cid:1681) de (cid:283)ient (cid:282)lood di(cid:418)e(cid:283)ted to lun(cid:322)s and o(cid:1681) (cid:418)i(cid:283)h di(cid:418)e(cid:283)ted to s(cid:482)stemi(cid:283) and head (cid:321)(cid:418)om r ao(cid:418)ta. When di(cid:475)in(cid:322), p(cid:418)essu(cid:418)e in l/r (cid:475)ent(cid:418)i(cid:283)les e(cid:417)ualizes (cid:282)lood (cid:500)lo(cid:476)s (cid:321)(cid:418)om r (cid:475)ent(cid:418)i(cid:283)le to l ao(cid:418)ta allo(cid:476)in(cid:322) mi(cid:481)in(cid:322) No (cid:418)eason (cid:321)o(cid:418) (cid:282)lood to lun(cid:322)s (cid:476)hile di(cid:475)in(cid:322) Spe(cid:283)ialized hemo(cid:322)lo(cid:282)in - mo(cid:418)e o(cid:1681) than an(cid:482) othe(cid:418) (cid:475)e(cid:418)te(cid:282)(cid:418)ate.
