Newly published fossil specimens discovered by an international team of scientists, including the Museum\u2019s Research Curator of Paleontology Dr. Christian Kammerer, are greatly expanding our knowledge of life at the ancient equator.<\/p>\n
The early Permian Period, roughly 285 million years ago, was a time of change for life on Earth: increased glaciation at the South Pole had caused the downfall of previously cosmopolitan \u201ccoal swamp\u201d environments, giving way to drier climates and new ecosystems.<\/p>\n
Prominent in these ecosystems were the amniotes, fully land-living animals with a shelled egg that meant, unlike amphibians, they did not need to return to the water to reproduce. Living amniotes include reptiles, birds and mammals, and the ancestors of these groups are represented in the Permian fossil record.<\/p>\n
Historically, the early Permian record of land animals was restricted to a set of rocks from the American Southwest, Appalachia and Central Europe, and what was happening on the southern continents at this time was largely unknown. However, recent fieldwork in the Pedra de Fogo Formation of northern Brazil, led by Dr. Juan Cisneros of the Universidade Federal do Piau\u00ed, has provided a valuable window into life in the tropical Permian just south of the equator.<\/p>\n
Early Permian Synapsids<\/strong><\/p>\n Two papers published in the past two weeks present strongly contrasting aspects of the Pedra de Fogo ecosystem. The first presents the first record of early Permian synapsids from South America. This group represents the ancestors of mammals and are well-represented globally in the later Permian and Triassic. Based on their abundance in early Permian rocks of Texas and Oklahoma, scientists expected that they should be present in southern hemisphere ecosystems as well, but their fossils remained elusive.<\/p>\n The first clue to their presence was the impression of a single vertebra (part of the backbone) found by Kammerer during a mid-day break \u2014 temperatures in this part of Brazil are so extreme (up to 120\u00ba F) that for health reasons it is necessary to enforce a \u201csiesta\u201d period when the scientists are not actively hiking and digging.<\/p>\n Hunkering down over a pile of rock fragments in the quarry, he spent hours carefully flipping each one over, looking for evidence of fossils and eventually finding half of a \u201cmold\u201d \u2014 the hollow left over from a bone that later dissolved. This bone looked different from the usual fish and amphibian vertebrae that are common at the locality, suggesting that it could represent an amniote.<\/p>\n Confirmation that amniotes (and specifically synapsids) were present came with the subsequent discovery of a maxilla (jawbone) showing the characteristic tooth structure of early synapsids. These finds demonstrate overlap between North and South American faunas in the early Permian, but the extreme rarity of synapsid fossils at the Brazilian sites suggest that the local environment was not ideal for them.<\/p>\n The Twisted Jaws of Tanyka<\/strong><\/p>\n The second paper describes a new species of stem-tetrapod named Tanyka amnicol<\/em>a. The presence of a stem-tetrapod in this ecosystem at all came as a surprise \u2014 this group consists of animals occupying the branch of the family tree between fish and amphibians, whose best-known members such as Tiktaalik<\/em> and Ichthyostega<\/em> lived nearly 100 million years before Tanyka<\/em>. Whereas the Pedra de Fogo synapsids are early records of a group whose heyday was still on the horizon, Tanyka<\/em> was something of a relic.<\/p>\n \u201cTanyka<\/em> is from an ancient lineage that we didn\u2019t know survived to this time, and it\u2019s also just a really strange animal. The jaw has this weird twist that drove us crazy trying to figure it out. We were scratching our heads over this for years, wondering if it was some kind of deformation,\u201d says Dr. Jason Pardo of the Field Museum in Chicago, the study\u2019s lead author. \u201cBut at this point, we\u2019ve got nine jaws from this animal, and they all have this twist, including the really well-preserved ones. So it\u2019s not a deformation.\u201d<\/p>\n The twisted jaws of Tanyka<\/em> are indicative of an unusual feeding style, unique among creatures known at its time. The surface of Tanyka\u2019s<\/em> jawbone is covered in a series of smaller teeth called denticles, which form a grinding surface sort of like a cheese grater. Scientists have yet to find the bones that would make up Tanyka\u2019s<\/em> upper jaw, but they imagine its top teeth and denticles were oriented similarly to the ones on the lower jaw.<\/p>\n \u201cWe expect the denticles on the lower jaw were rubbing up against similar teeth on the upper side of the mouth. The teeth would have been rasping against each other, in a way that\u2019s going to create a relatively unique way of feeding,\u201d says Pardo. In general, teeth that are able to grind against each other are used for crushing up plant material. \u201cBased on its teeth, we think that Tanyka<\/em> was a herbivore, and that it ate plants at least some of the time,\u201d says Cisneros.<\/p>\n The researchers say that it\u2019s surprising that a stem-tetrapod like Tanyka<\/em> would have evolved to eat plants, since most of its fellow stem-tetrapods only ate meat. \u201cIt indicates that even though Tanyka<\/em> was part of an archaic group, it\u2019s not like these were static and unchanging,\u201d says Kammerer. \u201cThey were still evolving and playing important roles in their ecosystems, even if they didn\u2019t end up surviving to the present day.\u201d<\/p>\n","protected":false},"author":6,"featured_media":119641,"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\/119639"}],"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":3,"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/news\/119639\/revisions"}],"predecessor-version":[{"id":119644,"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/news\/119639\/revisions\/119644"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/media\/119641"}],"wp:attachment":[{"href":"https:\/\/naturalsciences.org\/calendar\/wp-json\/wp\/v2\/media?parent=119639"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}