Tuesday, April 17, 2007

Early Amphibians Had A Big Bite

Terrestrial-style feeding in a very early aquatic tetrapod is supported by evidence from experimental analysis of suture morphology. M.J. Markey and C.R. Marshall. PNAS, Published online before print April 16, 2007.

Acanthostega. Photo by Jonathan Blair/NGS
Abstract [edit]: There is no consensus on when in the fish-tetrapod transition suction feeding, the primary method of prey capture in the aquatic realm, evolved into the direct biting on prey typical of terrestrial animals.

Here, we show that differences in the morphology of selected cranial sutures between species that span the fish-tetrapod transition (the Devonian osteolepiform fish Eusthenopteron, the aquatic Devonian tetrapod Acanthostega, and the Permian terrestrial tetrapod Phonerpeton) can be used to infer when terrestrial feeding first appeared.

Using this procedure, we find that the suture morphologies of Acanthostega are inconsistent with the hypothesis that it captured prey primarily by means of suction, which suggests that it may have bitten directly on prey at or near the water's edge.

Thus, our data strongly support the hypothesis that the terrestrial mode of feeding first emerged in aquatic taxa.

Read the press release at Nat. Geo. News.