Croc update

[KELL00BELL@aol.com]

       Mali dyrosaurs of Maastrichtian age occur in the same beds as lungfish--hardly pelagic taxa.  The paleoenvironment is considered to have been "marginal marine, possibly brackish."  This is consistent with my earlier view that dyrosaurs inhabited estuaries, not the open sea, and were vulnerable to tomistomine competition in the Eocene.
       Rhamphosuchus, recently reinterpreted as a tomistomine, vanished at the same horizon that Crocodylus appears, in the Siwalik section.  The tomistomines which radiated at the expense of pholidosaurs, including dyrosaurs, apparently succumbed in their turn to Crocodylus, as I suggested earlier.
       Rhamphosuchus was a relatively brevirostrine tomistomine with greater heterodonty than the others.  Unlike fully piscivorous tomistomines, it was more like Crocodylus, hence more likely to have competed with the latter, and evidently lost.  Even ordinary tomistomines were vulnerable.  Long, delicate snouts were susceptible to breakage, forcing tomistomines to yield to Crocodylus in every confrontation over prime nesting or basking sites, and enabling Crocodylus to steal fish caught by tomistomines with virtual impunity.
       -Tim