{"id":332549,"date":"2026-03-06T19:49:10","date_gmt":"2026-03-06T19:49:10","guid":{"rendered":"https:\/\/www.newsbeep.com\/ie\/332549\/"},"modified":"2026-03-06T19:49:10","modified_gmt":"2026-03-06T19:49:10","slug":"a-twisted-fossil-jaw-reveals-a-strange-275-million-year-old-animal","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ie\/332549\/","title":{"rendered":"A Twisted Fossil Jaw Reveals a Strange 275-Million-Year-Old Animal"},"content":{"rendered":"

\"A<\/a>Artist\u2019s reconstruction of Tanyka amnicola. Credit: Vitor Silva<\/p>\n

Paleontologists surveying a dry riverbed in northeastern Brazil repeatedly encountered the same type of fossil: a lower jaw about six inches long, curved and thick, and twisted in an unexpected way.<\/p>\n

A single specimen could have been written off as a distortion. But after the team recovered nine jaws from the Pedra de Fogo Formation<\/a>\u2014all preserving the same pronounced rotation in three dimensions\u2014they concluded the feature reflected normal anatomy rather than damage. <\/p>\n

In Proceedings of the Royal Society B<\/a>, the researchers describe the jaws as evidence of a distinct species and an unusual feeding apparatus from deep in tetrapod history.<\/p>\n

They named the animal Tanyka amnicola<\/a>, pairing ta\u00f1yk\u00e3, \u201cjaw\u201d in Guaran\u00ed, with a Latin term meaning \u201criver dweller.\u201d It lived about 275 million years ago, in the early Permian<\/a>, when this region formed part of Gondwana<\/a>. By that time, Tanyka belonged to a lineage of stem tetrapods that had largely disappeared elsewhere, persisting alongside groups that would later give rise to modern amphibians, reptiles, birds, and mammals.<\/p>\n

\u201cTanyka is from an ancient lineage that we didn\u2019t know survived to this time, and it\u2019s also just a really strange animal,\u201d Jason Pardo, the study\u2019s lead author, said in a statement. \u201cThe jaw has this weird twist that drove us crazy trying to figure it out.\u201d<\/p>\n

The Sideways Chew<\/p>\n

\"Diagram<\/a>Jaw rotation during mandibular adduction in Tanyka. (a) Jaw in closed position, lateral view; (b) jaw in closed position, anterior view; (c) jaw in open
position, lateral view; (d) jaw in open position, anterior view. General skull shape speculative, based on Baphetes<\/a>. Credit: Proceedings of Royal Society B<\/p>\n

The oddity begins with orientation. In most tetrapods, lower-jaw teeth point upward toward the roof of the mouth. In Tanyka, the researchers report, the mandible is strongly twisted so that the chewing surface faces partly outward rather than directly upward toward the palate.<\/p>\n

Along the top edge, the animal carried a row of relatively large teeth in the dentary. But the main chewing surface sat farther in, on a set of bones called the coronoids and a piece of bone near the front of the jaw. These elements bore a dense pavement of denticles\u2014small tooth-like bumps\u2014arranged into a broad pad far wider than the main tooth row.<\/p>\n

The paper describes the fossil as a \u201cremarkable battery\u201d of enlarged denticles on a strongly arched coronoid, with some denticles showing wear consistent with repeated contact during feeding.<\/p>\n

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\"\"<\/a>MAP-PV 097, close-up of symphysis, showing simple symphyseal surface and dentition (a). MAP-PV 662, close-up of coronoid denticles, showing wear (b). Scale increments equal 1 mm. Credit: Wikimedia Commons<\/p>\n

That sort of motion suggests a complex chewing pattern documented in the modern aquatic salamander Siren lacertina<\/a>, which uses three-dimensional jaw movements to rake food against palatal teeth.<\/p>\n

Because the team has not yet identified an upper jaw or skull bones that clearly match the mandibles, many details remain unknown. The twist would have made the denticle field\u2014not the outer tooth row\u2014the main point of contact with food. Researchers propose a feeding stroke that included long-axis rotation of the jaw, producing a rasping motion across the palate.<\/p>\n

What did Tanyka rasp? The paper frames the jaw as an adaptation for specialized processing of small invertebrates or for consuming some plant material. Still, Pardo said that \u201cwe expect the denticles on the lower jaw were rubbing up against similar teeth on the upper side of the mouth,\u201d creating \u201ca relatively unique way of feeding.\u201d<\/p>\n

And Juan Carlos Cisneros, a coauthor at the Federal University of Piau\u00ed, stated, \u201cBased on its teeth, we think that Tanyka was a herbivore, and that it ate plants at least some of the time.\u201d<\/p>\n

Gondwana\u2019s holdouts<\/p>\n

\"\"<\/a>Holotype jaw of the animal, MAP-PV 662. (a) lingual view of the fossil; (b) interpretive drawing in lingual view. Credit: Proceedings of Royal Society B<\/p>\n

If the jaw is the hook, the bigger story may be where Tanyka sits on the family tree.<\/p>\n

In two separate phylogenetic analyses, the authors recover Tanyka as an unambiguous stem tetrapod, with affinities to a cluster of mostly Carboniferous forms often called baphetid-grade tetrapods\u2014animals best documented from Laurussia, the northern supercontinent that once encompassed much of North America and Europe.<\/p>\n

Many paleontologists see the late Carboniferous as a major reset for early four-limbed animals. As climates dried\u2014a shift often discussed in connection with the Carboniferous Rainforest Collapse\u2014older stem-tetrapod lineages appear to fade from the record, while groups closer to today\u2019s amphibians and the first amniotes become more prominent. Tanyka doesn\u2019t fit that straightforward story, at least in Gondwana\u2019s southern ecosystems.<\/p>\n

This is not the first sign that Gondwana could shelter holdovers. The paper points to Gaiasia, a giant stem tetrapod from Namibia described in 2024, as another late-surviving relic with ties to lineages otherwise characteristic of earlier northern deposits. Together, the fossils suggest that \u201ccurrent hypotheses of Carboniferous tetrapod turnover are oversimplified,\u201d the authors write.<\/p>\n

The Pedra de Fogo Formation sits at the center of the team\u2019s case. In the paper, the authors describe it as the most extensive early Permian tetrapod assemblage yet known from Gondwana. Against that backdrop, Tanyka is the first tetrapod with baphetid-like affinities reported from Gondwana, and the only known Permian member of that broader grade, according to the researchers.<\/p>\n

For now, the animal remains mostly a mouth without a body. The holotype jaw measures 17.2 centimeters (about 6.8 inches), and one specimen is roughly 25% larger, but the team cannot yet anchor those jaws to a full skeleton. Pardo added that, by comparison to relatives, it might have looked \u201ckind of like a salamander with a slightly longer snout.\u201d That guess may change with the next field season\u2014perhaps when a paleontologist finally finds the rest of the twist.<\/p>\n","protected":false},"excerpt":{"rendered":"Artist\u2019s reconstruction of Tanyka amnicola. Credit: Vitor Silva Paleontologists surveying a dry riverbed in northeastern Brazil repeatedly encountered…\n","protected":false},"author":2,"featured_media":332550,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[153132,153133,97856,153134,9156,61,60,153135,153136,151606,153137,82,153138,153139],"class_list":["post-332549","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-brazil-fossils","tag-early-tetrapods","tag-fossil-discovery","tag-fossil-jaws","tag-gondwana","tag-ie","tag-ireland","tag-paleoecology","tag-pedra-de-fogo-formation","tag-permian-period","tag-prehistoric-animals","tag-science","tag-stem-tetrapods","tag-vertebrate-evolution"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/332549","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=332549"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/332549\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/332550"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=332549"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=332549"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=332549"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}