Richards Spur

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Two specimens of Captorhinus aguti found at Richards Spur Captorhinus aguti p.jpg
Two specimens of Captorhinus aguti found at Richards Spur

Richards Spur is a Permian fossil locality located at the Dolese Brothers Limestone Quarry north of Lawton, Oklahoma. The locality preserves clay and mudstone fissure fills of a karst system eroded out of Ordovician limestone and dolomite, with the infilling dating to the Artinskian stage of the early Permian (Cisuralian), around 289 to 286 million years ago. Fossils of terrestrial animals are abundant and well-preserved, representing one of the most diverse Paleozoic tetrapod communities known. [1] [2] A common historical name for the site is Fort Sill, in reference to the nearby military base. [3] Fossils were first reported at the quarry by workers in 1932, spurring a wave of collecting by local and international geologists. Early taxa of interest included the abundant reptile Captorhinus [4] [5] and microsaurs such as Cardiocephalus and Euryodus . [3] Later notable discoveries include Doleserpeton (one of the most lissamphibian-like Paleozoic tetrapods), [6] the most diverse assortment of parareptiles in the Early Permian, [7] and the rare early diapsid Orovenator . [8]

Contents

Geology

The caves of Richards Spur formed in the Ordovician-age Arbuckle Limestone, which was uplifted, exposed, and tilted into a vertical orientation within the Pennsylvanian and Permian. In the early Permian, a karst system formed within the limestone, complete with caves containing speleotherms (stalagmites, stalactites, cave popcorn, etc.) made of calcite. Most of the karsts are narrow, 40–60 cm (16-24 inches) in width, and vertically oriented. Due to active mining at the site constantly destroying and exposing new layers, the layout of the system has not been recorded. Most of the Permian infill is discarded in the quarry's waste dumps without sedimentological and stratigraphic data, hampering studies into those aspects of the locality. However, it is known that the lower sections of the system (25 meters or 82 feet below the surface) lacks fossil material. [1]

Various skulls of Delorhynchus cifellii recovered from Richards Spur, showing the excellent preservation common to the site. Delorhynchus cifellii skulls.png
Various skulls of Delorhynchus cifellii recovered from Richards Spur, showing the excellent preservation common to the site.

Many of the fossils of Richards Spur were found in soft calcareous claystone or conglomerate. They likely ended up in the caves as a result of water runoff from the surface, as indicated by the presence of surface minerals such as quartz, kaolinite, and sulfides among the fossils. Individual organisms may have been already disarticulated by scavenging or decomposition on the surface, decomposed within the caves after the fresh corpse had been washed in, or even died within the caves after becoming trapped. Organisms which became disarticulated on the surface experienced more wear and erosion on their fossils, induced by exposure to the elements and transportation by water within and/or outside the karst system. On the other hand, recently deceased or living organism would have been more articulated due to their decomposition occurring in the more stable cave environment, with their tendons keeping their individual bones in place prior to fossilization. The most complete fossils were encased in a residue which was almost completely calcite, indicating that the cave structures precipitated around their skeletons. The caves likely had to have been submerged in water (or at least persistently humid) for active speleotherm formation, and therefore this mode of spectacular preservation, to have been possible. Some fossils are encrusted by pyrite, indicating the presence of anoxic fluids or diagenesis in the systems at some point. Most (but not all) fossils are stained a dark color by seepage of hydrocarbons into the deposits. These assorted biochemical conditions are the likely cause of unusually variable Carbon isotope values found within different preserved speleotherms. [1]

Paleoenvironment

Isotope analysis of preserved speleotherms shows several regular fluctuations in δ18O levels within a time span of 1-20 thousand years. Similar fluctuations in modern low-latitude environments are considered to be indicative of strong variation in precipitation between wet and arid periods on the scales of centuries or millennia. Some trace elements agree with this data, as Barium and Phosphorus concentrations increase with higher δ18O (drier periods); this is explained by increased incorporation of dust and seafoam in drier, windier periods, as demonstrated by climatological analyses in a modern cave system in Israel. [9] [1]

Other than exceedingly rare fragments of xenacanthids and eryopoids, aquatic animals are practically absent from Richards Spur. Although amphibians are common at the site, most of them are terrestrially-adapted taxa such as dissorophoids, microsaurs, and seymouriamorphs. This is in strong contrast to contemporary floodplain environments in Oklahoma and Texas, which have abundant fossils of aquatic animals like Eryops and Diplocaulus , along with large lowland amniotes like Edaphosaurus . As a result, the site is considered to represent animals living in a drier environment upland from the humid floodplains which preserve most of the Permian red beds. The only other productive Early Permian geological locale commonly considered to preserve an upland community is the Tambach Formation of Germany. [10] [11] [2]

Age

The unique preservational environment of Richards Spur precludes geological stratigraphy. Based on the faunal composition (particularly the abundance of Captorhinus aguti , Cardiocephalus , and Euryodus ), Richards Spur has been considered roughly equivalent in age to the Arroyo Formation (Lower Clear Fork) of Texas. [3] [10] [12] In Oklahoma, the equivalent may be the upper Garber Formation or lower Hennessey Formation. [13] The South Grandfield site of the Hennessey Formation is an example of a more typical Oklahoman fossil locale which has similar captorhinid and microsaur taxa to Richards Spur. [2] To determine the absolute age of the Richards Spur deposits, the speleotherm studied for the Oxygen isotope and trace element analyses was also sampled for Uranium-Lead dating. It was determined that the speleotherm was formed between 289.68 and 288.32 million years ago. This time period was originally stated to be Sakmarian in age, [9] but after a later refinement to the ICS timescale, it was specified as belonging to the early Artinskian. Two more speleotherms studied later gave date ranges of 283.8 to 289.6 Ma, and 286.0 to 286.4 Ma, indicating that the locality was deposited over several million years. [1]

Fauna

Amphibians

Acheloma dunni , a trematopid temnospondyl [14]
Aspidosaurus sp., a dissorophid temnospondyl [15]
Cacops morrisi , a dissorophid temnospondyl [16]
Cacops woehri , a dissorophid temnospondyl [17]
Cardiocephalus peabodyi , a gymnarthrid microsaur [3]
Dissorophus multicinctus , a dissorophid temnospondyl [15]
Doleserpeton annectens , an amphibamid temnospondyl [6]
Euryodus primus , a gymnarthrid microsaur [3]
Llistrofus pricei , a hapsidopareiid microsaur [18]
Nannaroter mckinziei , an ostodolepid microsaur [19]
Pasawioops mayi , a micropholid temnospondyl [20]
Seymouria sp., a seymouriamorph [10]
Sillerpeton permianum , an aistopod [21]
Tersomius dolesensis , a micropholid temnospondyl [22]

Synapsids

Arisierpeton simplex , a caseid [23]
Dimetrodon sp., a sphenacodontid [24]
Mesenosaurus efremovi , a varanopid [25]
Mycterosaurus longiceps , a varanopid [12]
Oromycter dolesorum , a caseid [26]
Varanops brevirostris , a varanopid [12]

Parareptiles

Abyssomedon williamsi , a nyctiphruretid [27]
Bolosaurus grandis , a bolosaurid [28]
Colobomycter pholeter , a lanthanosuchoid [7]
Colobomycter vaughni , a lanthanosuchoid [29]
Delorhynchus cifellii , a lanthanosuchoid [30]
Delorhynchus multidentatus , a lanthanosuchoid [31]
Delorhynchus priscus , a lanthanosuchoid [30]
Feeserpeton oklahomensis , a lanthanosuchoid [32]
Microleter mckinzieorum , a basal parareptile [33]

Eureptiles

Baeotherates fortsillensis , a captorhinid [34]
Captorhinus aguti , a captorhinid [5]
Captorhinus kierani , a captorhinid [35]
Captorhinus magnus , a captorhinid [36]
Labidosauriscus richardi , a captorhinid [34]
Maiothisavros dianeae , a basal neodiapsid [37]
Opisthodontosaurus carrolli , a captorhinid [38]
Orovenator mayorum , a basal neodiapsid [8]

Invertebrates

Dolesea subtila , an indeterminate millipede [39]
Karstiulus fortsillensis, a xyloiuloid millipede [39]
Oklahomasoma richardsspurense , a juliform millipede [39]

Related Research Articles

<i>Cacops</i> Extinct genus of amphibians

Cacops, is a genus of dissorophid temnospondyls from the Kungurian stage of the early Permian of the United States. Cacops is one of the few olsoniforms whose ontogeny is known. Cacops fossils were almost exclusively known from the Cacops Bone Bed of the Lower Permian Arroyo Formation of Texas for much of the 20th century. New material collected from the Dolese Brothers Quarry, near Richards Spur, Oklahoma in the past few decades has been recovered, painting a clearer picture of what the animal looked and acted like.

<span class="mw-page-title-main">Dissorophidae</span> Extinct family of amphibians

Dissorophidae is an extinct family of medium-sized, temnospondyl amphibians that flourished during the late Carboniferous and early Permian periods. The clade is known almost exclusively from North America.

<span class="mw-page-title-main">Temnospondyli</span> Ancestors of modern amphibians adapted to life on land

Temnospondyli or temnospondyls is a diverse ancient order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carboniferous, Permian and Triassic periods, with fossils being found on every continent. A few species continued into the Jurassic and Early Cretaceous periods, but all had gone extinct by the Late Cretaceous. During about 210 million years of evolutionary history, they adapted to a wide range of habitats, including freshwater, terrestrial, and even coastal marine environments. Their life history is well understood, with fossils known from the larval stage, metamorphosis and maturity. Most temnospondyls were semiaquatic, although some were almost fully terrestrial, returning to the water only to breed. These temnospondyls were some of the first vertebrates fully adapted to life on land. Although temnospondyls are amphibians, many had characteristics such as scales and armour-like bony plates that distinguish them from the modern soft-bodied lissamphibians.

<i>Captorhinus</i> Extinct genus of reptiles

Captorhinus is an extinct genus of captorhinid reptiles that lived during the Permian period. Its remains are known from North America and possibly South America.

<i>Colobomycter</i> Extinct genus of reptiles

Colobomycter is an extinct genus of lanthanosuchoid parareptile known from the Early Permian of Oklahoma.

<span class="mw-page-title-main">Trematopidae</span> Extinct family of amphibians

Trematopidae is a family of dissorophoid temnospondyl spanning the late Carboniferous to the early Permian. Together with Dissorophidae, the family forms Olsoniformes, a clade comprising the medium-large terrestrial dissorophoids. Trematopids are known from numerous localities in North America, primarily in New Mexico, Oklahoma, and Texas, and from the Bromacker quarry in Germany.

<i>Euryodus</i> Extinct genus of amphibians

Euryodus is an extinct genus of microsaur within the family Gymnarthridae. Euryodus is a Lepospondyl from the clade Microsauria that lived during the Lower Permian. The name comes from Greek, meaning ‘broad-tooth’. It has been found in the southern half of North America, from its original discovery in Texas up to Utah.

<i>Delorhynchus</i> Extinct genus of reptiles

Delorhynchus is an extinct genus of lanthanosuchoid parareptile known from the late Early Permian Garber Formation of Comanche County, Oklahoma. It contains three species: the type species D. priscus is based on a series of maxillae. The second species to be described, D. cifellii, is known from a larger number of well-preserved skulls and skeletal material. The third species, D. multidentatus, is based on a fragmentary skull with several rows of teeth on its jaw.

<span class="mw-page-title-main">Acleistorhinidae</span> Extinct family of reptiles

Acleistorhinidae is an extinct family of Late Carboniferous and Early Permian-aged parareptiles. Acleistorhinids are most diverse from the Richards Spur locality of the Early Permian of Oklahoma. Richards Spur acleistorhinids include Acleistorhinus, Colobomycter, and possibly Delorhynchus and Feeserpeton. Other taxa include Carbonodraco from the Late Carboniferous of Ohio and Karutia from the Early Permian of Brazil. Acleistorhinidae is commonly considered a subgroup of lanthanosuchoids, related to taxa such as Chalcosaurus, Lanthaniscus and Lanthanosuchus. However, a re-examination of parareptile phylogeny conducted by Cisneros et al. (2021) argued that lanthanosuchids were not closely related to acleistorhinids. The phylogenetic analysis conducted by these authors recovered acleistorhinids as the sister group of the clade Procolophonia, while lanthanosuchids were recovered within the procolophonian subgroup Pareiasauromorpha.

Pasawioops is an extinct genus of early Permian dissorophoid temnospondyl within the clade Amphibamiformes.

Christian Alfred Sidor is an American vertebrate paleontologist. He is currently a Professor in the Department of Biology, University of Washington in Seattle, as well as Curator of Vertebrate Paleontology and Associate Director for Research and Collections at the Burke Museum of Natural History and Culture. His research focuses on Permian and Triassic tetrapod evolution, especially on therapsids.

<i>Microleter</i> Extinct genus of reptiles

Microleter is an extinct genus of basal procolophonomorph parareptiles which lived in Oklahoma during the Early Permian period. The type and only known species is Microleter mckinzieorum. Microleter is one of several parareptile taxa described from the Richards Spur fissure fills, and can be characterized from its high tooth count, lacrimal/narial contact, short postfrontal, and slit-like temporal emargination edged by the postorbital, jugal, squamosal, and quadratojugal. Contrary to Australothyris, which had a similar phylogenetic position as a basal procolophonomorph, Microleter suggests that early parareptile evolution occurred in Laurasia and that multiple lineages developed openings or emarginations in the temporal region.

<i>Rubeostratilia</i> Extinct genus of amphibians

Rubeostratilia is an extinct genus of amphibamiform temnospondyl from the early Permian of Texas. It is known from a single skull. This genus was named by Hélène Bourget and Jason S. Anderson in 2011, and the type species is Rubeostratilia texensis. The genus name comes from the Latin translation of 'redbeds' in reference to the Texas redbeds that produced both the holotype and many other early Permian fossils. The specific name is for the state of Texas. The holotype and only known specimen was collected in 1941 from the Nocona Formation exposures in Clay County by a Works Projects Administration project that was transferred to the Field Museum of Natural History through an interinstitutional exchange with the Texas Memorial Museum.

<i>Georgenthalia</i> Extinct genus of amphibians

Georgenthalia is an extinct genus of dissorophoid temnospondyl from the Lower Permian. It is an amphibamid which lived in what is now the Thuringian Forest of central Germany. It is known from the holotype MNG 11135, a small, complete skull. It was found in the Bromacker locality of the Tambach Formation. It was first named by Jason S. Anderson, Amy C. Henrici, Stuart S. Sumida, Thomas Martens and David S. Berman in 2008 and the type species is Georgenthalia clavinasica.

<span class="mw-page-title-main">Paleontology in Oklahoma</span>

Paleontology in Oklahoma refers to paleontological research occurring within or conducted by people from the U.S. state of Oklahoma. Oklahoma has a rich fossil record spanning all three eras of the Phanerozoic Eon. Oklahoma is the best source of Pennsylvanian fossils in the United States due to having an exceptionally complete geologic record of the epoch. From the Cambrian to the Devonian, all of Oklahoma was covered by a sea that would come to be home to creatures like brachiopods, bryozoans, graptolites and trilobites. During the Carboniferous, an expanse of coastal deltaic swamps formed in areas of the state where early tetrapods would leave behind footprints that would later fossilize. The sea withdrew altogether during the Permian period. Oklahoma was home a variety of insects as well as early amphibians and reptiles. Oklahoma stayed dry for most of the Mesozoic. During the Late Triassic, carnivorous dinosaurs left behind footprints that would later fossilize. During the Cretaceous, however, the state was mostly covered by the Western Interior Seaway, which was home to huge ammonites and other marine invertebrates. During the Cenozoic, Oklahoma became home to creatures like bison, camels, creodonts, and horses. During the Ice Age, the state was home to mammoths and mastodons. Local Native Americans are known to have used fossils for medicinal purposes. The Jurassic dinosaur Saurophaganax maximus is the Oklahoma state fossil.

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.

<i>Abyssomedon</i> Extinct genus of reptiles

Abyssomedon is an extinct genus of a nyctiphruretid parareptile known from Early Permian fissure fills at Richards Spur in Comanche County, Oklahoma, south-central United States. It contains a single species, Abyssomedon williamsi, which represents oldest known nyctiphruretid species and the first to be discovered in North America.

<span class="mw-page-title-main">Amphibamiformes</span> Extinct clade of amphibians

Amphibamiformes is an unranked clade with Dissorophoidea created by Schoch (2018). It encompasses all of the taxa traditionally considered to be "amphibamids", branchiosaurids, and hypothetically lissamphibians under the traditional temnospondyl hypothesis of lissamphibian origins. These taxa are typically small-bodied dissorophoids and form the sister group to Olsoniformes, which comprises dissorophids and trematopids.

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  27. ↑ Mark J. MacDougall and Robert R. Reisz (2014). "The first record of a nyctiphruretid parareptile from the Early Permian of North America, with a discussion of parareptilian temporal fenestration". Zoological Journal of the Linnean Society. 172 (3): 616–630. doi:10.1111/zoj.12180.
  28. ↑ Reisz, Robert R.; Barkas, Vaia; Scott, Diane (2002-03-14). "A new early Permian bolosaurid reptile from the Richards Spur Dolese Brothers Quarry, near Fort Sill, Oklahoma". Journal of Vertebrate Paleontology. 22 (1): 23–28. doi:10.1671/0272-4634(2002)022[0023:ANEPBR]2.0.CO;2. ISSN   0272-4634. S2CID   129050218.
  29. ↑ MacDougall, Mark J.; Modesto, Sean P.; Reisz, Robert R. (2016-09-02). "A new reptile from the Richards Spur locality, Oklahoma, U.S.A., and patterns of Early Permian parareptile diversification". Journal of Vertebrate Paleontology. 36 (5): e1179641. Bibcode:2016JVPal..36E9641M. doi:10.1080/02724634.2016.1179641. ISSN   0272-4634. S2CID   89333948.
  30. 1 2 Reisz, Robert R.; Macdougall, Mark J.; Modesto, Sean P. (2014-07-29). "A new species of the parareptile genus Delorhynchus, based on articulated skeletal remains from Richards Spur, Lower Permian of Oklahoma". Journal of Vertebrate Paleontology. 34 (5): 1033–1043. Bibcode:2014JVPal..34.1033R. doi:10.1080/02724634.2013.829844. ISSN   0272-4634. S2CID   128459194.
  31. ↑ Rowe, Dylan C. T.; Scott, Diane M.; Bevitt, Joseph J.; Reisz, Robert R. (2021). "Multiple Tooth-Rowed Parareptile From the Early Permian of Oklahoma". Frontiers in Earth Science. 9: 740. Bibcode:2021FrEaS...9..740R. doi: 10.3389/feart.2021.709497 . ISSN   2296-6463.
  32. ↑ Macdougall, Mark J.; Reisz, Robert (2012-09-01). "A new parareptile (Parareptilia, Lanthanosuchoidea) from the Early Permian of Oklahoma". Journal of Vertebrate Paleontology. 32 (5): 1018–1026. Bibcode:2012JVPal..32.1018M. doi:10.1080/02724634.2012.679757. ISSN   0272-4634. S2CID   86218618.
  33. ↑ Linda A. Tsuji; Johannes Muller; Robert R. Reisz (2010). "Microleter mckinzieorum gen. et sp. nov. from the Lower Permian of Oklahoma: the basalmost parareptile from Laurasia". Journal of Systematic Palaeontology. 8 (2): 245–255. Bibcode:2010JSPal...8..245T. doi:10.1080/14772010903461099. S2CID   129529082.
  34. 1 2 Modesto, Sean P.; Scott, Diane; Reisz, Robert R. (2018). "A new small captorhinid reptile from the lower Permian of Oklahoma and resource partitioning among small captorhinids in the Richards Spur fauna". Papers in Palaeontology. 4 (2): 293–307. Bibcode:2018PPal....4..293M. doi:10.1002/spp2.1109. ISSN   2056-2802. S2CID   135306015.
  35. ↑ deBraga, Michael; Bevitt, Joseph J.; Reisz, Robert R. (2019-05-15). "A New Captorhinid From the Permian Cave System Near Richards Spur, Oklahoma, and the Taxic Diversity of Captorhinus at This Locality". Frontiers in Earth Science. 7: 112. Bibcode:2019FrEaS...7..112D. doi: 10.3389/feart.2019.00112 . ISSN   2296-6463.
  36. ↑ Kissel, Richard A.; Dilkes, David W.; Reisz, Robert R. (2002-09-01). "Captorhinus magnus, a new captorhinid (Amniota: Eureptilia) from the Lower Permian of Oklahoma, with new evidence on the homology of the astragalus". Canadian Journal of Earth Sciences. 39 (9): 1363–1372. Bibcode:2002CaJES..39.1363K. doi:10.1139/e02-040. ISSN   0008-4077.
  37. ↑ Mooney, Ethan D.; Maho, Tea; Bevitt, Joseph J.; Reisz, Robert R. (2022-11-30). "An intriguing new diapsid reptile with evidence of mandibulo-dental pathology from the early Permian of Oklahoma revealed by neutron tomography". PLOS ONE. 17 (11): e0276772. Bibcode:2022PLoSO..1776772M. doi: 10.1371/journal.pone.0276772 . ISSN   1932-6203. PMC   9710763 . PMID   36449456.
  38. ↑ Reisz, R. R.; LeBlanc, Aaron R. H.; Sidor, Christian A.; Scott, Diane; May, William (2015-08-20). "A new captorhinid reptile from the Lower Permian of Oklahoma showing remarkable dental and mandibular convergence with microsaurian tetrapods". The Science of Nature. 102 (9): 50. Bibcode:2015SciNa.102...50R. doi:10.1007/s00114-015-1299-y. ISSN   1432-1904. PMID   26289932. S2CID   17161972.
  39. 1 2 3 Hannibal, Joseph T.; May, William J. (2021). "Permian millipedes from the Fort Sill fissures of southwestern Oklahoma, with comments on allied taxa and millipedes preserved in karstic environments". Journal of Paleontology. 95 (3): 586–600. Bibcode:2021JPal...95..586H. doi: 10.1017/jpa.2020.100 . ISSN   0022-3360.
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