Who Are the Heterostraci? – #UREES270 – 2018

Randle and Sansom, 2017, Phylogenetic relationships of the ‘higher heterostracans’ (Heterostraci: Pteraspidiformes and Cyathaspididae), extinct jawless fishes: Zoological Journal of the Linnean Society, v. 181, p. 910-926

What’s it about?

The Heterostraci are armored jawless fishes that are a sister group (evolutionary offshoot, if you will) to the lineage that later led to fishes with jaws. This paper is a discussion of how the various species of fish tucked into the Heterostraci are actually related.

Why does it matter?

This paper shows that it is important to consider stratigraphic ranges and other measures in order to more completely understand the evolutionary relationships among fossil organisms.

Why did I read this?

This is another paper that I have assigned as part of the agnathan fishes unit of the vertebrate paleontology course. In particular, it outlines important characters used to identify species of jawless fishes, and is a good opportunity to discuss how cladistic analysis works in paleontology.