{"id":622468,"date":"2026-08-05T21:12:16","date_gmt":"2026-08-05T21:12:16","guid":{"rendered":"https:\/\/www.europesays.com\/ie\/622468\/"},"modified":"2026-08-05T21:12:16","modified_gmt":"2026-08-05T21:12:16","slug":"tiny-new-primate-species-emerges-from-50-million-year-old-wyoming-sandstone","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/ie\/622468\/","title":{"rendered":"Tiny New Primate Species Emerges from 50-Million-Year-Old Wyoming Sandstone"},"content":{"rendered":"

Paleontologists working in southern Wyoming have identified a previously unknown species of omomyid primate, adding a new chapter to the story of one of the best-studied fossil lineages in North America.<\/strong><\/p>\n

\"Tetonius<\/a><\/p>\n

Tetonius homunculus (colorized) by R. Bruce Horsfall from W.B. Scott\u2019s History of Land Mammals in the Western Hemisphere.<\/p>\n

The new species belongs to a family of small, big-eyed, tarsier-like<\/a> primates called omomyids<\/a> that lived in the forests of North America roughly 50 million years ago (Eocene epoch).<\/p>\n

Named Tetonius varleyorum, the animal was comparable in size to a modern mouse lemur.<\/p>\n

\u201cOur paper is about a new species of an omomyid primate, a primate family close to the top of the family tree of modern primates \u2014 with lemurs on one side and apes, humans and monkeys on the other,\u201d said Parker Rhinehart, a doctoral student with the Biodiversity Institute and Natural History Museum at University of Kansas.<\/p>\n

\u201cThe branch point where they meet up at the top is where the omomyids fall.\u201d<\/p>\n

\u201cThey\u2019re true primates, but they\u2019re extinct. They appear about 55 or 56 million years ago across the northern hemisphere.\u201d<\/p>\n

Dozens of jaw and tooth fragments from Tetonius varleyorum was found at a single sandstone locality nicknamed Tim\u2019s Confession, part of the Smiley Draw local fauna in the Great Divide Basin.<\/p>\n

The site has already produced nearly 1,000 tooth-bearing jaw fragments representing a wide range of ancient mammals.<\/p>\n

\u201cIdentifying ancient primate fossils in the field typically requires hunting tiny fossil jaws and teeth \u2014 the only body parts tough enough to withstand erosion over geologic time,\u201d Rhinehart said.<\/p>\n

\u201cOur paper analyzes fossils from Smiley Draw, a different Wyoming locale outside of the better-sampled Bighorn Basin.\u201d<\/p>\n

\u201cThis is really important to the Tetonius story<\/a>,\u201d he added.<\/p>\n

\u201cBecause so many scientific ideas only really consider the fossils from the Bighorn Basin, they just don\u2019t take in the whole picture.\u201d<\/p>\n

\u201cOne of the things our paper points out is when you start incorporating fossils from outside of the Bighorn Basin, this picture becomes a little bit more complicated.\u201d<\/p>\n

What makes the new discovery of Tetonius varleyorum especially notable is not just the new species itself, but the company it kept.<\/p>\n

Alongside Tetonius varleyorum, the same site also yielded two other rare omomyid primates, Arapahovius gazini and Anemorhysis savage, only the second and third times either species has ever been documented.<\/p>\n

According to the paleontologists, three separate species of these small primates have never before been found living together at a single early Eocene site, and a fourth omomyid, not yet formally described, was also recovered there.<\/p>\n

\u201cOur description of Tetonius varleyorum as a new fossil species gives fresh detail to the biogeographic and evolutionary history of primates,\u201d Rhinehart said.<\/p>\n

\u201cA landmark 1987 paper<\/a> by paleontologists Thomas Bown and Kenneth Rose includes a famous figure depicting the evolution of fossil Tetonius jaws found in the Bighorn Basin.\u201d<\/p>\n

\u201cIt\u2019s upheld as a great example of an evolutionary transition \u2014 reflecting a true transition in the fossil record.\u201d<\/p>\n

\u201cWhile the earlier paper and figure have been vital to the Tetonius story, fossils from Smiley Draw would challenge some of its conclusions.\u201d<\/p>\n

\u201cThe 1987 paper claims that there is no branching of the tree, going from one intermediate species of Tetonius to the next with no branching speciation events. Evolutionary biologists call this anagenesis.\u201d<\/p>\n

\u201cOur analysis reveals that the new fossils of Tetonius varleyorum interrupt the purported anagenetic lineage from the Bighorn Basin.\u201d<\/p>\n

The team\u2019s paper<\/a> appears in the Journal of Human Evolution.<\/p>\n

_____<\/p>\n

Parker D. Rhinehart et al. 2026. A diverse new omomyid primate fauna from the early Eocene of southern Wyoming with implications for interpreting macroevolutionary patterns among anaptomorphines. Journal of Human Evolution 218, 103867; doi: 10.1016\/j.jhevol.2026.103867<\/p>\n","protected":false},"excerpt":{"rendered":"Paleontologists working in southern Wyoming have identified a previously unknown species of omomyid primate, adding a new chapter…\n","protected":false},"author":2,"featured_media":622469,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_share_on_mastodon":"0"},"categories":[77],"tags":[262951,18,100692,8101,4696,19,17,46508,1539,262952,46168,133,262953,19447,262954,262955,384,7035],"class_list":["post-622468","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-bighorn-basin","tag-eire","tag-eocene","tag-evolution","tag-fossil","tag-ie","tag-ireland","tag-jaw","tag-north-america","tag-omomyidae","tag-primate","tag-science","tag-smiley-draw","tag-teeth","tag-tetonius","tag-tetonius-varleyorum","tag-united-states","tag-wyoming"],"share_on_mastodon":{"url":"","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/622468","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/comments?post=622468"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/622468\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media\/622469"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media?parent=622468"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/categories?post=622468"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/tags?post=622468"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}