Tristichopterids are members of the Tetrapodamorpha, the group of lobe fin fishes amongst which tetrapods emerged. Examples recovered from Late Devonian strata (roughly 380-360 Ma) show an evolutionary series demonstrating increasing tetrapod-likeness. Increasingly powerful limbs and shoulder bones and the evolution of a neck, characterize the elpistostegid grade tetrapodomorphs such as Tiktaalik, Elpistostege and the less well known but no less spectacular, Panderichthys from Russia.
Tristichopterids are the sister group of elpistostegids and digitate (finger and toe bearing) tetrapods, providing the last group of typically fish-like tetrapodomorphs. As such they are of great interest in understanding the series of morphological changes leading to the emergence of true tetrapods. Hyneria udlezinye Locality: Waterloo Farm Age: latest Devonian A giant tristichopterid, the largest bony fish from the Waterloo Farm locality, Hyneria udlezinye ('the one who eats others') is known from various isolated bones and scales, many of them from a single two metre long individual, though other bones from the site indicate individuals almost three metres in length (1). The size of the animal is estimated by comparison with the body proportions of the more completely understood tristichopterid Mandageria from Canowindra, Australia. Given its large size and battery of sharp fangs, this would have been the top predator inhabiting the Waterloo lagoon. Hyneria udlezinye is very similar to Hyneria lindae from the Catskill formation of New York State, but differs slightly in the proportions of some of the bones. These two occurrences of the genus are the only ones known. The great distance and latitude that would have separated these two occurrences tells us that the Late Devonian world is poorly sampled, and the distribution of this fish would have been much wider than the fossil record indicates. References: 1) Gess RW, Ahlberg PE (2023) A high latitude Gondwanan species of the Late Devonian tristichopterid Hyneria (Osteichthyes: Sarcopterygii). PLoS ONE 18(2): e0281333. https://doi.org/10.1371/journal.pone.0281333 Further reading; palaeoblog.blogspot.com/2006/01/ears-evolved-from-fish-gills.htm |