The newly-identified species of tristichopterid fish grew up to 3 m (10 feet) long and belongs to the extinct genus Hyneria.
Life reconstruction of the non-marine component of the Waterloo Farm ecosystem: Hyneria udlezinye is shown together with the tetrapods Umzantsia amazana and Tutusius umlambo, the placoderms Groenlandaspis riniensis and Bothriolepis africana, the coelacanth Serenichthys kowiensis, the lungfish Isityumzi mlomomde, and a cyrtoctenid eurypterid. Image credit: Maggie Newman / R.W. Gess.
Hyneria udlezinye roamed the prehistoric oceans during the Devonian period, about 360 million years ago.
The new species is a member of Tristichopteridae, a diverse and successful group of tetrapodomorph fishes that existed throughout the Middle and Late Devonian epochs.
Within this group sizes ranged from a few tens of centimeters (genus Tristichopterus) to several meters (Hyneria and Eusthenodon).
“Tristichopterid fishes represent the sister group of elpistostegalians and digit bearing tetrapods,” said Dr. Robert Gess from the Albany Museum and Geology Department at Rhodes University and Professor Per Ahlberg from the Department of Organismal Biology at Uppsala University.
“They achieved a worldwide distribution during the later part of the Devonian period, before becoming extinct during the end-Devonian mass extinction event.”
“Most known species have either been recovered from the tropical to subtropically deposited sediments of Euramerica or alternately from Australia which, towards the end of the Devonian, formed the low latitude northern rim of Gondwana.”
Several fossilized specimens of Hyneria udlezinye were found in the Gondwanan high-latitude lagerstätte at Waterloo Farm near Makhanda/Grahamstown in South Africa.
The preserved material comprises most of the dermal skull, lower jaw, gill cover and shoulder girdle.
“The Hyneria material from Waterloo Farm consists predominantly of dermal bones, though some elements of the axial skeleton and paired fins are also preserved,” the paleontologists noted.
“Material is preserved in muddy carbonaceous metashale.”
“The total body length of the holotype individual of Hyneria udlezinye was in the range of 1.8-1.9 m; some isolated bones, however, come from larger individuals,” they added.
“An isolated cleithrum, for example, is 50% larger than that of the type specimen, suggesting a possible body length of at least 2.7 m for this individual. This size range is similar to other giant tristichopterids.”
Hyneria udlezinye most closely resembles a previously known species, Hyneria lindae, from the Catskill Formation of Pennsylvania, the United States.
“The largest osteichthyan member of the Waterloo Farm vertebrate assemblage, a predatory sarcopterygian with a probable maximum length of nearly 3 m, proves to be a new species of the genus Hyneria,” the researchers said.
“This genus is otherwise only recorded from the Catskill Formation of Pennsylvania.”
“Hyneria udlezinye differs from the type species Hyneria lindae in a number of minor but securely attested proportional characters relating to the skull roof, cheek, lower jaw and operculum.”
“Hyneria now joins Eusthenodon and Langlieria as one of the derived, late, giant tristichopterids known from both Euramerica and Gondwana,” they added.
“The other confirmed members of this clade (Mandageria, Cabonnichthys and Edenopteron) are exclusively known from Gondwana.”
“This strongly supports the contention that this clade represents a Gondwanan radiation.”
The findings appear online in the journal PLoS ONE.
_____
R.W. Gess & P.E. Ahlberg. 2023. A high latitude Gondwanan species of the Late Devonian tristichopterid Hyneria (Osteichthyes: Sarcopterygii). PLoS ONE 18 (2): e0281333; doi: 10.1371/journal.pone.0281333
