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March 4, 2026<\/p>\n
2 min read<\/p>\n
Add Us On Google<\/span>Add SciAm<\/span><\/span><\/p>\n This may be the oldest \u2018butthole\u2019 imprint on Earth<\/p>\n Fossils show exceptionally rare evidence of a cloacal vent\u2014the slit that most vertebrates use to excrete, have sex and lay egg\u2014which could shed light on the evolution of the orifice<\/p>\n By Taylor Mitchell Brown edited by Andrea Thompson<\/span><\/p>\n Fossil impression of the hind limb, tail and cloacal vent of Cabarzichnus pulchrus, a small lizard-like reptile.<\/p>\n Around 299 million years ago volcanic eruptions buried a patch of mud in what is today central Germany. Amid impressions of scales, tails and feet that fossilized in the patch was something else: Earth\u2019s oldest known \u201cbutthole\u201d imprint.<\/p>\n \u201cFinding an impression of [an] animal squatting in the mud and preserved with such fidelity is quite a scoop,\u201d says Jakob Vinther, a paleontologist at the University of Bristol in England, who was not involved with a new study describing the find in Current Biology. \u201cThe animal literally cemented itself\u2014and its nether regions\u2014into eternal history like the movie stars on the Hollywood Walk of Fame.\u201d<\/p>\n The structure imprinted into the fossilized mud is a slit that is technically called a cloaca. Unlike marsupials and placental mammals that split their \u201cbusiness elements\u201d into separate orifices, \u201cmost other animals have the Swiss Army knife equivalent of a rear opening,\u201d Vinther says. This gives them \u201cone opening for everything\u2014pooping, peeing, sex and laying eggs.\u201d<\/p>\n If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.<\/p>\n Lead author Lorenzo Marchetti, a paleontologist at the Natural History Museum of Berlin, discovered the vent while scrutinizing rare diagonal and hexagonal scale imprints in the fossil. \u201cI noticed something unusual, and after a comparison with modern animals, it became clear what it was,\u201d he says.<\/p>\n A closer look at the fossilized impression of the cloacal vent.<\/p>\n Cloacal vents vary in size and shape across the reptile world, but a lack of fossil preservation has kept their evolution mysterious.<\/p>\n \u201cOnly two examples of this structure are currently known in fossil reptiles,\u201d Marchetti says. They are this one and that of a 130-million-year-old ceratopsian called Psittacosaurus, which Vinther and his colleagues reported in 2021. Radioisotopes of ash within the new fossil suggest its cheeky impressions were planted about 170 million years before the Psittacosaurus fossil.<\/p>\n The scale imprints and footprints in the ancient muck helped Marchetti and his colleagues to determine that the derriere belonged to a never-before-named species. The animal, which the researchers named Cabarzichnus pulchrus, was a small lizardlike reptile that had likely been lounging in the mud to cool off, Marchetti says.<\/p>\n \u201cIt\u2019s pretty remarkable to see the fine details preserved of such a small animal,\u201d says Phil Bell, a paleontologist at the University of New England in Australia, who was not involved with the research. \u201cThe consistency of the mud has to be absolutely perfect for such an imprint to occur.\u201d<\/p>\n Fossil cloacae \u201care as rare as hens\u2019 teeth,\u201d Vinther says, \u201cand finding another one is exciting to say the least.\u201d<\/p>\n If you enjoyed this article, I\u2019d like to ask for your support. 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I hope you\u2019ll support us in that mission.<\/p>\n","protected":false},"excerpt":{"rendered":" March 4, 2026 2 min read Add Us On GoogleAdd SciAm This may be the oldest \u2018butthole\u2019 imprint on Earth Fossils show exceptionally rare evidence of a cloacal vent\u2014the slit that most vertebrates use to excrete, have sex and lay egg\u2014which could shed light on the evolution of the orifice By Taylor Mitchell Brown edited<\/p>\n","protected":false},"author":1,"featured_media":45820,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[58],"tags":[23532,23531,23533,7008,4742],"class_list":{"0":"post-45819","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-butthole","9":"tag-fossilized","10":"tag-imprint","11":"tag-oldest","12":"tag-worlds"},"_links":{"self":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts\/45819","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=45819"}],"version-history":[{"count":0,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts\/45819\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/media\/45820"}],"wp:attachment":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=45819"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=45819"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=45819"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}On supporting science journalism<\/h2>\n
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