| Zenaspidida | |
|---|---|
| |
| Fossil of Zenaspis powriei | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | †Osteostraci |
| Order: | †Zenaspidida Stensiö, 1958 |
| Subgroups | |
| Synonyms | |
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Zenaspida | |
Zenaspidida is an extinct order of osteostracans, a group of jawless stem-gnathostomes.[1] They possessed a distinct headshield, which varied in width to length ratio by species.
- ^ Scott, B. R.; Wilson, M. V. H. (2013). "A new species of osteostracan from the Lochkovian (Early Devonian) of the Mackenzie Mountains, with comments on body size, growth, and geographic distribution in the genus Machairaspis". Canadian Journal of Earth Sciences. 50 (2): 127–134. doi:10.1139/cjes-2012-0100.