{"id":114258,"date":"2025-09-17T11:35:14","date_gmt":"2025-09-17T15:35:14","guid":{"rendered":"https:\/\/naturalsciences.org\/calendar\/?post_type=news&p=114258"},"modified":"2025-09-18T13:39:51","modified_gmt":"2025-09-18T17:39:51","slug":"teen-pachycephalosaur-butts-into-fossil-record","status":"publish","type":"news","link":"https:\/\/naturalsciences.org\/calendar\/news\/teen-pachycephalosaur-butts-into-fossil-record\/","title":{"rendered":"\u2018Teen\u2019 Pachycephalosaur Butts Into Fossil Record"},"content":{"rendered":"

A \u201cteenaged\u201d pachycephalosaur from Mongolia\u2019s Gobi Desert may provide answers to lingering questions around the dinosaur group, according to new research published today in the journal Nature<\/em>. The fossil represents a new species of pachycephalosaur and is both the oldest and most complete skeleton of this dinosaur group found to date.<\/p>\n

\u201cPachycephalosaurs are iconic dinosaurs, but they\u2019re also rare and mysterious,\u201d says Lindsay Zanno, head of paleontology at the North Carolina Museum of Natural Sciences, associate research professor at North Carolina State University and corresponding author of the work.<\/p>\n

The specimen was discovered in the Khuren Dukh locality of the Eastern Gobi Basin by Tsogtbaatar Chinzorig from the Mongolian Academy of Sciences, who is the lead author of the paper and currently a research assistant at NC State.<\/p>\n

The new species is called Zavacephale rinpoche<\/em>, which is the combination of zava, meaning \u201croot\u201d or \u201corigin\u201d in Tibetan, and cephal, meaning \u201chead\u201d in Latin. The specific name, \u201crinpoche,\u201d or \u201cprecious one\u201d in Tibetan, refers to the domed skull discovered exposed on a cliff like a cabochon jewel.<\/p>\n

Z. rinpoche<\/em> lived around 108 million years ago during the Early Cretaceous period in what is now Mongolia\u2019s Gobi Desert. At the time, the area was a valley dotted with lakes and surrounded by cliffs or escarpments. Pachycephalosaurs were plant eaters, and adults could grow to around 14 feet long (4.3 meters) and seven feet tall (2.1 meters), weighing 800 – 900 pounds (363 \u2013 410 kilograms).<\/p>\n

\u201cZ. rinpoche<\/em> predates all known pachycephalosaur fossils to date by about 15 million years,\u201d Chinzorig says. \u201cIt was a small animal \u2013 about three feet or less than one meter long \u2013 and the most skeletally complete specimen yet found.\u201d<\/p>\n

The Z. rinpoche<\/em> specimen the team discovered was not fully grown when it died. However, it already sported a fully formed dome, though without much of the additional ornamentation found on other pachycephalosaur fossils.<\/p>\n

\u201cZ. rinpoche<\/em> is an important specimen for understanding the cranial dome development of pachycephalosaurs, which has been debated for a long time due to the absence of early diverging or pre-Late Cretaceous species and the fragmentary nature of nearly all pachycephalosaurian fossils,\u201d Chinzorig says.<\/p>\n

How to tell whether two skulls that look different belong to two distinct species or just different growth stages of the same species is a long-standing debate for paleontologists who study this group, and that\u2019s where Z. rinpoche<\/em> comes in.<\/p>\n

\u201cPachycephalosaurs are all about the bling, but we can\u2019t use flashy signaling structures alone to figure out what species they belong to or what growth stage they\u2019re in because some cranial ornamentation changes as animals mature,\u201d Zanno says.<\/p>\n

\u201cWe age dinosaurs by looking at growth rings in bones, but most pachycephalosaur skeletons are just isolated, fragmentary skulls,\u201d Zanno adds. \u201cZ. rinpoche<\/em> is a spectacular find because it has limbs and a complete skull, allowing us to couple growth stage and dome development for the first time.\u201d<\/p>\n

By examining a thin slice of the specimen\u2019s lower leg bone, the researchers determined that, despite sporting a fully formed dome, this Z. rinpoche<\/em> was still a juvenile when it died.<\/p>\n

Pachycephalosaurs are famous for their large domed skulls and are often depicted using those domes to duel in epic headbutting contests. \u201cThe consensus is that these dinosaurs used the dome for socio-sexual behaviors,\u201d Zanno says. \u201cThe domes wouldn\u2019t have helped against predators or for temperature regulation, so they were most likely for showing off and competing for mates.\u201d<\/p>\n

Z. rinpoche<\/em> fills in huge gaps in the pachycephalosaur timeline \u2013 both in terms of when they lived and how they grew, the researchers say.<\/p>\n

\u201cThis specimen is a once-in-a-lifetime discovery. It is remarkable for being the oldest definitive pachycephalosaur, pushing back the fossil record of this group by at least 15 million years, but also because of how complete and well-preserved it is,\u201d Zanno says. \u201cZ. rinpoche<\/em> gives us an unprecedented glimpse into the anatomy and biology of pachycephalosaurs, including what their hands looked like and that they used stomach stones to grind food.\u201d<\/p>\n

\u201cThe newly recovered materials of Z. rinpoche<\/em>, such as the hand elements, the stomach stones (gastroliths), and an articulated tail with covered tendons, reshape our understanding of the paleobiology, locomotion, and body plan of these ‘mysterious’ dinosaurs,\u201d Chinzorig says.<\/p>\n","protected":false},"author":6,"featured_media":114259,"menu_order":0,"template":"","format":"standard","meta":{"_links_to":"","_links_to_target":""},"acf":[],"_links":{"self":[{"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/news\/114258"}],"collection":[{"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/news"}],"about":[{"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/types\/news"}],"author":[{"embeddable":true,"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/users\/6"}],"version-history":[{"count":0,"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/news\/114258\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/media\/114259"}],"wp:attachment":[{"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/media?parent=114258"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}