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The new fossils mark the southernmost record of Tenontosaurus yet found, pushing the animal\u2019s known range into West Texas.<\/p>\n
For paleontologists, the site reframes the early Cretaceous Southwest, filling a rare gap in the dinosaur fossil record.<\/p>\n
Rocks that stood out<\/p>\n
The work was led by Dr. Ricketts at The University of Texas at El Paso (UTEP<\/a>).\u00a0His research focuses on how rock layers, faults, and fossils together reveal the long geological history of the Southwest.<\/p>\n Dr. Ricketts was mapping sedimentary rock at the Indio Mountains Research Station, a field site about 26 miles southwest of Van Horn.<\/p>\n While hiking across soft shale during a long day in the field, he noticed darker pieces that didn\u2019t look like the surrounding rock.<\/p>\n Identifying the plant-eating dinosaur<\/p>\n The scattered pieces came from the tail and leg of Tenontosaurus, a herbivore that could reach more than 20 feet long.<\/p>\n Paleontologists classify Tenontosaurus as an ornithopod, a two-legged, plant-eating dinosaur related to duck-billed forms.<\/p>\n Much of what we know about Tenontosaurus tilletti comes from a monograph<\/a> describing Cloverly Formation fossils in Montana and Wyoming.\u00a0<\/p>\n More recently, a high resolution cranial study<\/a> used CT scanning to reconstruct the skull of Tenontosaurus in exceptional detail.\u00a0<\/p>\n Elusive fossils from the early Cretaceous <\/p>\n Compared with later dinosaur-bearing rocks, early Cretaceous formations in North America yield few skeletons and often preserve only scattered bones.<\/p>\n Researchers studying the Western Interior have shown that Late Cretaceous dinosaur faunas are sampled more completely than older parts of the record.\u00a0<\/p>\n That imbalance means new early Cretaceous finds like the West Texas bones carry more weight than their fragmentary appearance might suggest.<\/p>\n A recent quantitative analysis<\/a> reveals a strong Late Cretaceous bias in fossil sampling, with earlier intervals poorly represented.<\/p>\n Yucca formation as river land<\/p>\n The bones weathered out of the Yucca Formation, a Lower Cretaceous rock unit that preserves ancient river systems in what is now West Texas.<\/p>\n In the Eagle Mountains, earlier work identified the Yucca Formation as the oldest Cretaceous unit in the area.<\/p>\n Recent carbon-isotope profile<\/a> data show that Yucca Formation layers span the Aptian, an Early Cretaceous age used by geologists.\u00a0<\/p>\n The results further indicate the Albian, the next Early Cretaceous age after the Aptian, within Yucca strata \u2013 placing their boundary near the upper part of the formation.\u00a0<\/p>\n Pushing the dinosaur range southwest<\/p>\n The West Texas fossil is assigned to cf. Tenontosaurus sp., a designation indicating that the bones resemble Tenontosaurus but lack all of its diagnostic features.<\/p>\n A detailed paper<\/a> describes the specimen and explains why it most closely resembles known Tenontosaurus skeletons.\u00a0<\/p>\n Even with that careful identification, the new site lies hundreds of miles from previous tenontosaur finds in Arizona and north-central Texas.<\/p>\n Mapped across the Western Interior, Tenontosaurus now stretches from Cloverly sites along the Montana-Wyoming border down to far West Texas.<\/p>\n How a few bones tell a story<\/p>\n At the Indio Mountains site, the dinosaur is represented by three tail vertebrae and the end of a femur, plus smaller fragments.<\/p>\n Those bones include features such as tall hexagonal centra and a stout femur with distinctive condyles, closely matching better-known Tenontosaurus skeletons.<\/p>\n Because the bones came from carefully dated rock<\/a> layers, they act as time stamps tying Tenontosaurus and the Yucca Formation together.<\/p>\n Together, the anatomy and the age data indicate that the West Texas animal fits within a wider population of early Cretaceous plant eaters.<\/p>\n Implications of the discovery <\/p>\n Tenontosaurus shared its world with large predators, smaller plant eaters, and early flowering plants that were just starting to diversify on land.<\/p>\n In other formations, Tenontosaurus bones occur alongside fossils of the predator Deinonychus and the giant carnivore Acrocanthosaurus, hinting at similar food webs.\u00a0<\/p>\n Rivers and lakes in the Yucca Formation would have supplied vegetation, providing food for herds of medium-sized herbivores like Tenontosaurus.<\/p>\n Finding this dinosaur<\/a> in far West Texas suggests those ecosystems extended farther south than many researchers expected for this Cretaceous interval.<\/p>\n Patience in the field<\/p>\n Dr. Ricketts first spotted the fossils while working with a graduate student, and then returned with his family to help collect the pieces.<\/p>\n \u201cI wasn\u2019t out looking for fossils that day. We were studying the rocks in the area when I noticed fragments weathering out of soft shale,\u201d said Dr. Ricketts.<\/p>\n The discovery shows that carefully walking new exposures, even on land scientists have explored many times, can still reveal significant surprises.<\/p>\n Geologic<\/a> mapping, which might look routine, often produces benefits for paleontology and other fields.<\/p>\n Each newly documented fossil locality at the Indio Mountains Research Station strengthens the case for protecting university research lands in the desert Southwest.<\/p>\n For scientists, the story is a reminder that patience in the field can lead to discoveries never predicted.<\/p>\n A piece of the Southwest puzzle<\/p>\n With the West Texas specimen, researchers can compare its age and setting to other Tenontosaurus sites across North America<\/a>.<\/p>\n The comparisons may eventually reveal whether animals in the southern range lived with different climates, plants, or predators than their northern relatives.<\/p>\n Future work at the site could uncover teeth, additional limb bones, or trackways showing how Tenontosaurus moved across soft river margins.<\/p>\n The study is published in the New Mexico Museum of Natural History and Science Bulletin<\/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.\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 routine day of mapping rocks in West Texas changed when geologist Jason W. Ricketts noticed strange bone…\n","protected":false},"author":3,"featured_media":498924,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[159,67,132,68],"class_list":{"0":"post-498923","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-science","9":"tag-united-states","10":"tag-unitedstates","11":"tag-us"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@us\/115853910968378113","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/498923","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/comments?post=498923"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/498923\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media\/498924"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media?parent=498923"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/categories?post=498923"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/tags?post=498923"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}