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Two pebble-sized rock pieces from southern Brazil held a tiny skull and jaw, pressed flat but still intact.<\/p>\n
Rebuilding those fragments in 3D, paleontologist Dr. Fl\u00e1vio Augusto Pretto at the Universidade Federal de Santa Maria (UFSM<\/a>) identified a hatchling.<\/p>\n Unworn teeth and thin bones let Pretto\u2019s UFSM team treat the animal as a hatchling<\/a>, not a small adult.<\/p>\n Even at that age, the skull carried enough landmarks to compare with adults, yet it still lacked some finishing touches.<\/p>\n A rhynchosaur hatchling fossil<\/p>\n The analysis placed the hatchling among rhynchosaurs, plant-eating reptiles<\/a> that spread across wide Triassic landscapes.<\/p>\n Instead of simple pointed teeth, many rhynchosaurs grew upper tooth plates<\/a> that met a blade on the lower jaw.<\/p>\n Across southern Brazil, scientists have named only five rhynchosaur species<\/a>, so a baby adds a rare new data point.<\/p>\n That early snapshot matters because young skulls can look unfamiliar, yet they capture growth steps adults no longer show.<\/p>\n Teeth show age<\/p>\n Clean tooth<\/a> tips marked the fossil as a perinate, a baby still near hatching age. With little wear, the teeth had not yet scraped against tough plants, which usually dulls edges in adults.<\/p>\n Several adult markers still appeared, including a reinforced mouth edge and a lower-jaw shape built for tight closure.<\/p>\n Because teeth keep developing after hatching, some dental clues can look incomplete even when they belong to the right species.<\/p>\n Growing more tooth rows<\/p>\n Over time, rhynchosaurs added rows as their jaws widened, leaving young animals with simpler dental patterns.<\/p>\n New teeth likely formed behind older ones, and the chewing surface expanded as the skull grew longer and deeper.<\/p>\n In the Brazilian hatchling, only one row showed on each side of the upper tooth plate. Such early simplicity can make a newborn seem closer to distant relatives, even when it belongs inside a well-known branch.<\/p>\n When lineages mislead<\/p>\n To sort the hatchling into a lineage, the team ran a phylogenetic analysis, a method for mapping how species are related.<\/p>\n Including tooth-row counts pushed the fossil toward a more primitive spot, and several known species fell out of place.<\/p>\n Removing that age-sensitive feature let the skull return to the expected branch, and the displaced species returned too.<\/p>\n That swing showed why baby traits can scramble relationships, especially when scientists compare species by counts that change with growth.<\/p>\n A cautious species call<\/p>\n Detailed comparisons in the paper linked the hatchling to Macrocephalosaurus mariensis, a species known from southern Brazil. One groove on the upper tooth plate and two tooth rows on the lower jaw matched that species best.<\/p>\n At the Buriol Site in Rio Grande do Sul, Brazil\u2019s far south, the find hinted at two close relatives living together.<\/p>\n Such overlap raises the stakes for getting juvenile traits right, since a misread tooth row could inflate diversity.<\/p>\n Where the rocks sit<\/p>\n Layered red rocks at the Buriol Site held the hatchling, but the exact layer still lacks a direct date.<\/p>\n Nearby rock layers limit the deposit to about 233 million years ago, near the middle of the Late Triassic.<\/p>\n At that time, rivers and floodplains covered parts of southern Brazil, burying bones quickly enough for rare baby fossils to survive.<\/p>\n Because hatchlings decay fast and attract scavengers, even one well-preserved skull can reshape what a site seems to contain.<\/p>\n Scanning without breaking<\/p>\n An accidental break would have ruined the skull, so the team avoided physical preparation on the fragile pieces.<\/p>\n Using micro-CT scanning, a 3D X-ray method for tiny objects, they mapped each bone without touching it.<\/p>\n \u201cThe fossil is indeed very fragile, so any accidental break during preparation would be practically irreversible,\u201d said Pretto.<\/p>\n That scan also revealed how the teeth sat in the jaw, details that would have stayed buried in stone.<\/p>\n More fossils likely<\/p>\n Field crews from UFSM kept returning to the Buriol Site, and the team expected more bones from the same rock layers.<\/p>\n Each new juvenile could fill gaps between hatchlings and adults, letting scientists track when tooth rows and ridges appear.<\/p>\n \u201cWe visit the site several times per year, and it is still yielding fossils, so more discoveries shall be announced in the future!\u201d said Pretto.<\/p>\n More hatchlings would also test whether that tentative identification holds, or whether a close cousin shared the same baby teeth.<\/p>\n Small skull, big caution<\/p>\n That tiny skull showed that some jaw traits matured early, while tooth patterns kept changing as rhynchosaurs grew.<\/p>\n Better growth series from Buriol could help scientists avoid mistaking youth for ancestry when they classify new fossils.<\/p>\n The study is published in Journal of Systematic Palaeontology<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.<\/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 fossil skull barely 1 inch long has proved to be a newborn reptile from Brazil\u2019s Late Triassic,…\n","protected":false},"author":2,"featured_media":336355,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[61,60,82],"class_list":{"0":"post-336354","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-ie","9":"tag-ireland","10":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/336354","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=336354"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/336354\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/336355"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=336354"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=336354"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=336354"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}