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Researchers have now given it a name: Arenaerpeton supinatus, Latin for supine sand creeper. The fossil captures a moment from the Early Triassic, only a few million years after Earth\u2019s worst mass extinction.<\/p>\n
Lachlan J. Hart<\/a>, a PhD candidate in the School of Biological, Earth and Environmental Sciences at UNSW<\/a> Sydney and the Australian Museum<\/a> led the research that brought this animal out of obscurity and into the scientific record.<\/p>\n From garden stones to science<\/p>\n In 2023, the formal description of the specimen appeared in a peer reviewed journal, establishing Arenaerpeton supinatus as a new member of a Gondwanan amphibian family. <\/p>\n The paper documents an articulated skeleton preserved on its back with traces of soft tissue around the body.<\/p>\n \u201cThis fossil<\/a> is a unique example of a group of extinct animals known as temnospondyls, which lived before and during the time of the dinosaurs,\u201d Hart explained. <\/p>\n \u201cWe do not often find skeletons with the head and body still attached, and the soft tissue preservation is an even rarer occurrence.\u201d<\/p>\n Decoding the Arenaerpeton fossil<\/p>\n Arenaerpeton had a broad, low skull and a sturdy frame. The rock holds impressions of the body outline that suggest a heavy build, plus long ribs and stout limb bones.<\/p>\n The teeth tell another story. Along the jaws run many small marginal teeth, and on the roof of the mouth sit a pair of tusk like fangs. Those features point to a predator that seized slippery prey and did not let go.<\/p>\n Estimates put the total length around 4 feet. The UNSW team adds a precise figure from the fossil evidence, noting it was \u201cestimated to be about 1.2m from head to tail,\u201d said Hart. <\/p>\n The comparison highlights head shape, not close kinship, since the fossil lineage followed its own path long before modern salamanders appeared.<\/p>\n Where and when Arenaerpeton lived<\/p>\n The animal came from the Sydney Basin, a stack of sandstones and shales that record rivers, swamps, and lakes in what is now New South Wales. Its host rock belongs to the Terrigal Formation, a unit laid down during the Early to Middle Triassic.<\/p>\n High precision U Pb zircon ages from nearby volcanic ash layers in the Garie Formation cluster near 248 million years. <\/p>\n Those tuffs bracket the time when these river sands accumulated and help anchor Arenaerpeton in Earth\u2019s timeline.<\/p>\n Waters in this basin carried fish<\/a>, including species such as Cleithrolepis, and the skull and teeth of Arenaerpeton fit a life spent ambushing prey in slow channels. <\/p>\n Fine sands and plant fragments surrounding the skeleton point to burial in a quiet setting, not a raging flood.<\/p>\n The preservation includes a broad halo of soft tissue around the ribs. That band shows the body outline without mineralized skin armor and hints at how the carcass settled before final burial.<\/p>\n Family with staying power<\/p>\n Arenaerpeton belongs to chigutisaurids, a branch of temnospondyls, the diverse early amphibian grade tetrapods that flourished before and during the age of dinosaurs. These animals radiated across southern continents when they were joined in Gondwana.<\/p>\n Their history in Australia stretches across much of the Mesozoic. <\/p>\n An annotated checklist<\/a> of Australian Mesozoic tetrapods notes that chigutisaurids persisted into the Early Cretaceous, with Koolasuchus from Victoria representing the youngest known temnospondyl anywhere.<\/p>\n Arenaerpeton sits earlier in that story, close to the recovery interval after the end Permian crisis. <\/p>\n The size of this animal, coupled with features shared with later giants, hints at a long lived strategy that worked in varied climates and ecosystems.<\/p>\n \u201cThe fossil<\/a> record of temnospondyls spans across two mass extinction events, so perhaps this evolution of increased size aided in their longevity,\u201d said Hart. He points to body size as a possible advantage over deep time.\u00a0<\/p>\n Placing Arenaerpeton on the tree<\/p>\n The team assessed traits across the skull, palate, lower jaw, shoulder girdle, and forelimb, then compared them with other Triassic and Jurassic relatives. <\/p>\n Those comparisons place Arenaerpeton within Chigutisauridae alongside taxa from India and South America.<\/p>\n The analysis used a matrix of skeletal characters tested with parsimony methods. Results group Arenaerpeton with derived chigutisaurids, not with brachyopids that shared the basin at times.<\/p>\n Several features support that placement. The animal has many small marginal teeth, a narrow flat cultriform process on the palate, and adjacent intercentra in the vertebral column, a suite consistent with chigutisaurid identity.<\/p>\n Why Arenaerpeton matters now<\/p>\n Beyond taxonomic placement, this fossil fills a geographic and temporal gap in Australia\u2019s record. It is the first chigutisaurid named from New South Wales and shows that large bodied forms were already present early in the Triassic.<\/p>\n It also shows how science advances through community care as much as field campaigns. A homeowner saved a strange slab, museum staff preserved it, and researchers returned to it with new questions.<\/p>\n \u201cThis is one of the most important fossils found in New South Wales in the past 30 years, so it is exciting to formally describe it,\u201d said Dr. Matthew McCurry<\/a>, Senior Lecturer at UNSW and Curator of Palaeontology at the Australian Museum. The fossil is now part of the public story of the basin that buried it.<\/p>\n Arenaerpeton brings texture to a time often sketched in broad strokes. It offers a body outline, not just a list of bones, and it anchors a local river system to the global narrative of recovery after catastrophe.<\/p>\n The study is published in the Journal of Vertebrate Paleontology<\/a>.<\/p>\n Photo credit: UNSW Sydney\/Richard Freeman.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.\u00a0<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"A pile of garden stones on Australia\u2019s Central Coast held more than landscaping material. Inside one slab lay…\n","protected":false},"author":2,"featured_media":385511,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[70,16,15],"class_list":{"0":"post-385510","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-science","9":"tag-uk","10":"tag-united-kingdom"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@uk\/115118989956896526","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/385510","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/comments?post=385510"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/posts\/385510\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media\/385511"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/media?parent=385510"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/categories?post=385510"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/uk\/wp-json\/wp\/v2\/tags?post=385510"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}