[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Warm-Blooded debate
In a message dated 97-06-18 10:35:40 EDT, firstname.lastname@example.org (Jonathon Woolf)
<< Ectotherms have
no endurance because they can only generate energy anaerobically. >>
Too bad you haven't been able to find _A Cold Look at Warm-Blooded
Dinosaurs_, because it contains a key paper by Regal and Gans on the role of
the four-chambered heart in aerobic metabolism. Endothermy is only loosely
connected with endurance in tetrapods; the four-chambered heart much more so.
Since crocs >almost< have four-chambered hearts, and birds have them, we can
use the Extant Phylogenetic Bracket to argue that all dinosaurs, which are
phylogenetically between crocs and birds, had them. This, rather than
endothermy--which developed much later, perhaps only in the theropod lineage
that eventually evolved into birds--was necessarliy responsible for
dinosaurs' erect stance and cruising ability.