Why Can’t We Tell If a Chordate Is a Vertebrate in the Fossil Record? – #365papers – 2018 – 35

Sansom, Gabbott, and Purnell, 2010, Non-random decay of chordate characters causes bias in fossil interpretation: Nature, v. 463, 797-800.

What’s it about?

The authors observed the decay to two very similar organisms: amphioxus (Branchiostoma), a chordate, and the ammocoete larva (Lampetra), a vertebrate. It was observed that the distinctive characters that distinguish vertebrates from other chordates very quickly decay after death, resulting in both amphioxus and the ammocoete appearing to be merely stem chordates. 

Why does it matter?

The main conclusion is that our inferences about affinities of fossils as chordates or vertebrates, may be incorrect due to the effects of decay and fossilization.

Why did I read this?

This paper seems very relevant to one I read earlier this year on the Tully Monster. One argument that the Tully Monster was not a vertebrate as the lack to clearly preserved, diagnostically vertebrate features. This paper may turn up again in some class some day…