The Red Beds of Texas and Oklahoma are a group of Early Permian-age geologic strata in the southwestern United States cropping out in north-central Texas and south-central Oklahoma. They comprise several stratigraphic groups, including the Clear Fork Group, the Wichita Group, and the Pease River Group. [1] The Red Beds were first explored by American paleontologist Edward Drinker Cope starting in 1877. [2] Fossil remains of many Permian tetrapods (four-limbed vertebrates) have been found in the Red Beds, including those of Dimetrodon , Edaphosaurus , Seymouria , Platyhystrix , and Eryops . A recurring feature in many of these animals is the sail structure on their backs. [3]
Deposits dating from the Permian are present contiguously stretching from central Texas all the way into southern Nebraska. [4] In Nebraska and Kansas, deposits of light-colored limestone are frequent, while red-colored rocks are rare. In Oklahoma, the light-colored limestone transitions gradually into red-colored sandstone and shale until the limestone is virtually nonexistent in north-central Texas. [5] The portion of the red beds with abundant fossil deposits is in Texas between the Red River and the Salt Fork Brazos River. [6] The area includes the city of Wichita Falls, and rural communities such as Seymour and Archer City. [7]
The Texas and Oklahoma red beds are sedimentary rocks, mostly consisting of sandstone and red mudstone. [8] The red color of the rocks is due to the presence of ferric oxide. [9] The rocks were deposited during the early Permian in a warm, moist climate, [10] with seasonal periods of dry conditions. [11]
The Texas and Oklahoma red beds can be split into three primary stratigraphic groups: the Wichita Group, the Clear Fork Group, and the Pease River Group. The Wichita Group is the oldest of the three groups, having been deposited in the Sakmarian age. [12] The Wichita Group contains some of the richest fossil deposits in the red beds, including the Geraldine Bonebed in Archer County. [12] The Pease River Group is the most recent deposition, occurring during the Guadalupian epoch. [12] The Clear Fork Group is in between the other two, being deposited during the Kungurian age. [1] The stratigraphic groups are layered such that the Pease River Group overlies the Clear Fork Group, which overlies the Wichita group. [1]
From youngest to oldest:
In 1877, Edward Drinker Cope was the first paleontologist to study the red beds in search of fossils. [2] Cope employed collectors to aid him in his search for bones, including Swiss botanist Jacob Boll. After Boll's death in 1880 while collecting, Cope employed preacher W.F. Cummins to continue the search. [6] After Cope, paleontologists such as Ermine Cowles Case [13] and Alfred Romer [14] found rich deposits of Permian-era tetrapods.
The most prolific fossil site in the red beds is the Geraldine Bonebed within the Nocona Formation of the Wichita Group. [6] During the Permian, the bonebed was the site of a freshwater pond. After a catastrophic event this became the burial site for a variety of terrestrial and marine animals. [15] As a result, the bonebed contains a cross-section of life during the early Permian. Plant remains found in the bonebed include Calamites , ferns, and conifers. [6] Marine life present in the bonebed include Xenacanthus , [12] ostracods, and lungfish. [6] The Geraldine Bonebed is most famous as a prolific source of temnospondyls, synapsids, basal reptiliomorphs and reptiles, including partial and complete skeletons of Archeria , Eryops , Edaphosaurus , Dimetrodon , Bolosaurus , Trimerorhachis , Zatrachys , and Ophiacodon . [12]
The Clear Fork Group also contains multiple fossil sites. Like the Geraldine Bonebed and other Wichita Group sites, the Clear Fork Group is most famous for its early Permian amphibian deposits, especially Seymouria baylorensis . The species and genus were first discovered in 1904 by German paleontologist Ferdinand Broili. [16] Seymouria baylorensis is named for the location of its discovery in Baylor County near the city of Seymour. As one of the few Seymouria bone sites in the world, paleontologists have studied the Clear Fork deposit for evidence of Seymouria as a transitional fossil between aquatic and terrestrial animals, as well as Seymouria's close relationship to amniotes. [17] [18]
The Clear Fork Group also contains deposits of plant species throughout its different sections. The increasing prevalence of seed plants with pockets of water-based plants can be used to infer a wet, but drying climate. [11]
Wichita County is a county located in the U.S. state of Texas. As of the 2020 census, its population was 129,350. The county seat is Wichita Falls. The county was created in 1858 and organized in 1882. Wichita County is part of the Wichita Falls, Texas, TX metropolitan statistical area.
Baylor County is a county located in the U.S. state of Texas. As of the 2020 census, its population was 3,465. Its county seat is Seymour.
Archer County is a county located in the U.S. state of Texas. As of the 2020 census, its population was 8,560. Its county seat is Archer City. It is part of the Wichita Falls metropolitan statistical area.
Seymour is a city in and the county seat of Baylor County, Texas, United States. Its population was 2,575 as of the 2020 Census.
Eryops is a genus of extinct, amphibious temnospondyls. It contains the single species Eryops megacephalus, the fossils of which are found mainly in early Permian rocks of the Texas Red Beds, located in Archer County, Texas. Fossils have also been found in late Carboniferous period rocks from New Mexico. Several complete skeletons of Eryops have been found in lower Permian rocks, but skull bones and teeth are its most common fossils.
Dimetrodon is a genus of non-mammalian synapsid that lived during the Cisuralian age of the Early Permian period, around 295–272 million years ago. It is a member of the family Sphenacodontidae. With most species measuring 1.7–4.6 m (5.6–15.1 ft) long and weighing 28–250 kg (62–551 lb), the most prominent feature of Dimetrodon is the large neural spine sail on its back formed by elongated spines extending from the vertebrae. It was an obligate quadruped and had a tall, curved skull with large teeth of different sizes set along the jaws. Most fossils have been found in the Southwestern United States, the majority of these coming from a geological deposit called the Red Beds of Texas and Oklahoma. More recently, its fossils have also been found in Germany and over a dozen species have been named since the genus was first erected in 1878.
Orthacanthus is an extinct genus of fresh-water xenacanthid sharks, named by Louis Agassiz in 1836, ranging from the Upper Carboniferous until the Lower Permian. Orthacanthus had a nektobenthic life habitat, with a carnivorous diet. Multiple sources have also discovered evidence of cannibalism in the diet of Orthacanthus and of "filial cannibalism" where adult Orthacanthus preyed upon juvenile Orthacanthus. The genus Orthacanthus has been synonymized with Dittodus, Didymodus, and Diplodus.
Diadectes is an extinct genus of large reptiliomorphs or synapsids that lived during the early Permian period. Diadectes was one of the first herbivorous tetrapods, and also one of the first fully terrestrial vertebrates to attain large size.
Seymouria is an extinct genus of seymouriamorph from the Early Permian of North America and Europe. Although they were amphibians, Seymouria were well-adapted to life on land, with many reptilian features—so many, in fact, that Seymouria was first thought to be a primitive reptile. It is primarily known from two species, Seymouria baylorensis and Seymouria sanjuanensis. The type species, S. baylorensis, is more robust and specialized, though its fossils have only been found in Texas. On the other hand, Seymouria sanjuanensis is more abundant and widespread. This smaller species is known from multiple well-preserved fossils, including a block of six skeletons found in the Cutler Formation of New Mexico, and a pair of fully grown skeletons from the Tambach Formation of Germany, which were fossilized lying next to each other.
Secodontosaurus is an extinct genus of "pelycosaur" synapsids that lived from between about 285 to 272 million years ago during the Early Permian. Like the well known Dimetrodon, Secodontosaurus is a carnivorous member of the Eupelycosauria family Sphenacodontidae and has a similar tall dorsal sail. However, its skull is long, low, and narrow, with slender jaws that have teeth that are very similar in size and shape—unlike the shorter, deep skull of Dimetrodon, which has large, prominent canine-like teeth in front and smaller slicing teeth further back in its jaws. Its unusual long, narrow jaws suggest that Secodontosaurus may have been specialized for catching fish or for hunting prey that lived or hid in burrows or crevices. Although no complete skeletons are currently known, Secodontosaurus likely ranged from about 2 to 2.7 metres (7–9 ft) in length, weighing up to 110 kilograms (250 lb).
Diplocaulus is an extinct genus of lepospondyl amphibians which lived from the Late Carboniferous to the Late Permian of North America and Africa. Diplocaulus is by far the largest and best-known of the lepospondyls, characterized by a distinctive boomerang-shaped skull. Remains attributed to Diplocaulus have been found from the Late Permian of Morocco and represent the youngest-known occurrence of a lepospondyl.
Ermine Cowles Case, invariably known as E.C. Case, was a prominent American paleontologist in the second generation that succeeded Othniel Charles Marsh and Edward Drinker Cope. A graduate of the University of Kansas, with a PhD from the University of Chicago (1896), Case became a paleontologist of international stature while working at the University of Michigan. He was a Member of the American Philosophical Society (1931).
Parioxys is an extinct genus of temnospondyl amphibian from the Early Permian of Texas.
The exposed strata at the surface in and around Wichita Falls are the products of one ancient period of deposition with a modest amount of recent and modern alteration. In all cases, the strata are products of terrigenous (non-marine) environments dominated by fluvial depositional and erosional systems.
Paleontology in Texas refers to paleontological research occurring within or conducted by people from the U.S. state of Texas. Author Marian Murray has said that "Texas is as big for fossils as it is for everything else." Some of the most important fossil finds in United States history have come from Texas. Fossils can be found throughout most of the state. The fossil record of Texas spans almost the entire geologic column from Precambrian to Pleistocene. Shark teeth are probably the state's most common fossil. During the early Paleozoic era Texas was covered by a sea that would later be home to creatures like brachiopods, cephalopods, graptolites, and trilobites. Little is known about the state's Devonian and early Carboniferous life. Evidence indicates that during the late Carboniferous the state was home to marine life, land plants and early reptiles. During the Permian, the seas largely shrank away, but nevertheless coral reefs formed in the state. The rest of Texas was a coastal plain inhabited by early relatives of mammals like Dimetrodon and Edaphosaurus. During the Triassic, a great river system formed in the state that was inhabited by crocodile-like phytosaurs. Little is known about Jurassic Texas, but there are fossil aquatic invertebrates of this age like ammonites in the state. During the Early Cretaceous local large sauropods and theropods left a great abundance of footprints. Later in the Cretaceous, the state was covered by the Western Interior Seaway and home to creatures like mosasaurs, plesiosaurs, and few icthyosaurs. Early Cenozoic Texas still contained areas covered in seawater where invertebrates and sharks lived. On land the state would come to be home to creatures like glyptodonts, mammoths, mastodons, saber-toothed cats, giant ground sloths, titanotheres, uintatheres, and dire wolves. Archaeological evidence suggests that local Native Americans knew about local fossils. Formally trained scientists were already investigating the state's fossils by the late 1800s. In 1938, a major dinosaur footprint find occurred near Glen Rose. Pleurocoelus was the Texas state dinosaur from 1997 to 2009, when it was replaced by Paluxysaurus jonesi after the Texan fossils once referred to the former species were reclassified to a new genus.
The Archer City Formation is a geological formation in north-central Texas, preserving fossils from the Asselian and early Sakmarian stages of the Permian period. It is the earliest component of the Texas red beds, introducing an tropical ecosystem which will persist in the area through the rest of the Early Permian. The Archer City Formation is preceded by the cool Carboniferous swamp sediments of the Markley Formation, and succeeded by the equally fossiliferous red beds of the Nocona Formation. The Archer City Formation was not named as a unique geological unit until the late 1980s. Older studies generally labelled its outcrops as the Moran or Putnam formations, which are age-equivalent marine units to the southwest.
The Arroyo Formation, sometimes termed the Lower Clear Fork Formation, is a geologic formation in Texas. It preserves fossils dating back to the Kungurian stage of the Permian period. It is the lower-most portion of the Clear Fork Group, part of a series of fossiliferous Permian strata in the south-central United States known as the red beds.
The El Cobre Canyon Formation is a geologic formation in New Mexico. It preserves fossils dating back to the late Pennsylvanian to early Permian periods.
The Coyote Butte Limestone (OR085) is a geologic formation in Oregon. It preserves fossils dating back to the Sakmarian to Kungurian stages of the Permian period, spanning an estimated 23 million years. The formation occurs in isolated buttes to the north; Triangulation Hill, and south; type locality and name giver Coyote Butte and Tuckers Butte, on either side of the Grindstone and Twelvemile Creeks in Crook County, Oregon.
The Organ Rock Formation or Organ Rock Shale is a formation within the late Pennsylvanian to early Permian Cutler Group and is deposited across southeastern Utah, northwestern New Mexico, and northeastern Arizona. This formation notably outcrops around Canyonlands National Park, Natural Bridges National Monument, and Monument Valley of northeast Arizona, southern Utah. The age of the Organ Rock is constrained to the latter half of the Cisuralian epoch by age dates from overlying and underlying formations. Important early terrestrial vertebrate fossils have been recovered from this formation in northern Arizona, southern Utah, and northern New Mexico. These include the iconic Permian terrestrial fauna: Seymouria, Diadectes, Ophiacodon, and Dimetrodon. The fossil assemblage present suggests arid environmental conditions. This is corroborated with paleoclimate data indicative of global drying throughout the early Permian.