Birgeria: a big predator almost in the lineage of tetrapods in the LRT

There were many taxa close to the lineage of tetrapods in the LRT. 
Here’s one more (Figs. 1, 3). Birgeria, a one meter, maybe 2 meter-long predator derived from tetrapod-ancestor killers like Onychodus and basal to anchovies, like Engraulis, in the LRT.

Figure 1. Birgeria in situ and reconstructed by Romano and Brinkman 2009, colors added here. The lateral nasal is reidentified here as the prefrontal based on phylogenetic bracketing.

Figure 1. Birgeria in situ and reconstructed by Romano and Brinkman 2009, colors added here. The lateral nasal is reidentified here as the prefrontal based on phylogenetic bracketing.

The deeply-forked tail,
streamlined muscular tuna-like body and strong fins mark Birgeria as a fast-swimming pelagic (open seas) predator.

Figure 2. Engraulis the anchovy.

Figure 2a. Engraulis the anchovy.

Figure 2. Engraulis skull greatly resembles that of Clupeopsis.

Figure 2b. Engraulis skull greatly resembles that of
Clupeopsis.

Birgeria stensioei (Agassiz 1844; Romano and Brinkman 2009; Late Triassic; 1-2m, PIMUZ T4780) is a large, carnivorous late-survivor of a Silurian radiation that linked Pteronisculus and Engraulis to Strunius in the lineage of tetrapods. The scales were reduced to an area over the deeply forked caudal fin. The palatine teeth were larger than the marginal maxillary teeth.

Figure x. Newly revised fish subset of the LRT

Figure x. Newly revised fish subset of the LRT

Distinct from Romano and Brinkman,
the large bones anterolateral to the orbits are here identified as prefrontals, not nasals. Romano and Brinkman did not provide a cladogram. All known specimens are from the Triassic, but this genus must have been part of the Late Silurian radiation of pre-lobefin fish.


References
Agassiz L 1833-1844.  Recherches sur les poissons fossiles, 1-5. – 1420 pp.; Neuchâtel (Petitpierre).
Romano C and Brinkman W 2009. Reappraisal of the lower actinopterygian Birgeria stensioei ALDINGER, 1931 (Osteichthyes; Birgeriidae) from the Middle Triassic
of Monte San Giorgio (Switzerland) and Besano (Italy). Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen. 252: 17–31.

wiki/Birgeria

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