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Peabody's legacy: the Moenkopi Formation (Middle Triassic, Anisian) tetrapod ichnofauna—updates from an extensive new tracksite in NE Arizona, USA
Abstract
The Lower-Middle Triassic Moenkopi Group/Formation in the southwestern USA has yielded a famous tetrapod skeletal and ichnofossil fauna. A new locality in the Holbrook Member of the Moenkopi Formation (Anisian) of northeastern Arizona
appears to be the most extensive Middle Triassic tetrapod tracksite in North America. The ichnofossil-bearing level is close to the base of the Holbrook Member and several meters below the overlying Shinarump Formation (Upper Triassic, Carnian) of the Chinle Group. The track-bearing bed is a mudstone layer overlain by a massive-to-laminar, tabular sandstone body that represents sheet-like non-channelized flow deposited by flooding and preserves the collected natural casts of the tracks. A low diversity invertebrate ichnoassemblage dominated by Scoyenia on the track-bearing surface represents the Scoyenia ichnofacies. The paleoenvironment can be characterized as an intermittently subaerial/subaqueous setting on a nonmarine riverine floodplain. The tetrapod ichnoassemblage is dominated by archosaur tracks with the chirotheriids Chirotherium barthii, C. rex, Isochirotherium marshalli, Synaptichnium diabloense, S. pseudosuchoides, and small Rotodactylus cursorius. Synaptichnium and Rotodactylus are the most abundant tetrapod ichnogenera at this location. Chirotheres occur with different size classes, possibly suggesting a mixed archosaur community with individuals of different growth stages and ages. Biostratigraphically, the composition of the assemblage and the presence of the ichnospecies Chirotherium barthii in the Holbrook Member indicate the Chirotherium barthii biochron for this unit. The lack of Chirotherium sickleri supports former conclusions about paleobiogeographic peculiarities of the North American assemblage, if compared to early Anisian ichnoassociations of Europe, where Chirotherium barthii is commonly associated with C. sickleri. Interestingly, the new tracksite lacks archosauromorph/lepidosauromorph tracks such as Rhynchosauroides or therapsid tracks such as Dicynodontipus
that co-occur at other localities.
... (1) North America (Olsen and Baird, 1986;Weems, 1987Weems, , 1992Fraser and Olsen, 1996;Klein et al., 2006;Hunt and Lucas, 2007a;Lucas et al., 2010;Klein and Lucas, 2010b;Lockley and Lucas, 2013;Lockley et al., 2021;Milner et al., 2021;Klein et al., 2024), (2) Greenland (Klein et al., 2015a;Lallensack et al., 2017), (3) South America (Melchor and De Valais, 2006;Apesteguía et al., 2021), (4) Europe, Italy (Mietto, 1987;Leonardi and Lockley, 1995;Avanzini and Leonardi, 2002;Nicosia and Loi, 2003;Avanzini and Wachtler, 2012), Poland (Fuglewicz et al., 1990;Ptaszy nski, 2000;Nied zwiedzki and Ptaszynski, 2007;Klein and Nied zwiedzki, 2012), Germany (Karl and Haubold, 1998;Klein, 2000, 2002;Haubold, 2003, 2004;Kunz, 2004, 2011;Klein and Lucas, 2018;Marchetti et al., 2020b), France (Courel and Demathieu, 2000;Demathieu and Demathieu, 2004;Gand et al., 2000, Switzerland (Cavin et al., 2012;Klein et al., 2016), and Great Britain (King et al., 2005;Clark andCorrance, 2009), Spain (Pérez-López, 1993;Gand et al., 2010;Mujal et al., 2017Mujal et al., , 2018Navarro and Moratalla, 2018;De Jaime Soguero et al., 2021;see Díaz-Martínez and Pérez-García, 2012;Díaz-Martínez et al., 2015;Klein and Lucas, 2021 for overview and literature therein); (5) Southern Africa (Olsen and Galton, 1984;D'Orazi Porchetti and Nicosia, 2007;Marchetti et al., 2019bMarchetti et al., , 2020Abrahams et al., 2022), (6) North Africa (Klein et al., , 2011Lagnaoui et al., 2012Lagnaoui et al., , 2016Zouheir et al., 2020;Moreau et al., 2024), and (7) China Xing et al., 2013a;Xing and Klein, 2019). Reviews of the ichnotaxonomy of global ichnotaxa have been given by Lockley et al. (2006a,b), Lucas (2013, 2021), Klein et al. (2015b), and Lucas et al. (2014). ...
... Olenekian, LootsbergianeNonesian; (2) Protochirotherium, EarlyeLate Olenekian, Nonesian; (3) Chirotherium barthii, Late OlenekianeLate Anisian, NonesianePerovkan; (4) AtreipuseGrallator, Late AnisianeLadinian, PerovkaneBerdyankanian); (5) Brachychirotherium, CarnianeRhaetian, OtischalkianeApachian. More recently the Chirotherium barthii biochron was revised, and the FAD corrected to the Early Anisian, Perovkan (Klein et al., 2023b(Klein et al., ,2024. Lucas (2006, 2007c) introduced terminology for the study of tetrapod footprint ichnofacies. ...
In their review of Triassic tetrapod footprints, Klein and Lucas (2024) note that chirotheriid archosaur trackways from the famous Buntsandstein locality of Hildburghausen in Germany were the first scientifically described and named footprints. Triassic tetrapod footprint assemblages are relatively diverse, and, besides chirotheriids, other archosaur ichnotaxa are often abundant, such as the small dinosauromorph Rotodactylus from Middle Triassic deposits or tridactyl dinosauriform-dinosaurian forms such as Grallator and Atreipus, which are common in the Late Triassic. Sauropodomorpha are represented by the ichnogenera Pseudotetrasauropus, Tetrasauropus, Eosauropus, and Evazoum, the former two originally described from the Upper Triassic of southern Africa. Other common footprints, from some surfaces documented by mass occurrences, are the small lacertoid track Rhychosauroides (archosauromorph/lepidosauromorph). More rare are Procolophonichnium (procolophonid/therapsid), cynodont, and dicynodont therapsid footprints such as Dicynodontipus, Pentasauropus, and Therapsipus, and anamniote footprints such as Batrachichnus, tracks of turtles such as Chelonipus and of marine nothosaurs and placodonts (Dikoposichnus, Anshunpes).
Lower Triassic (Olenekian) footprint assemblages are known mostly from Europe (Volpriehausen, Detfurth, and Wióry formations, Germany, Poland), North America (Lower Moenkopi and Red Peak formations, Arizona,Wyoming), and North Africa (Timezgadiouine Formation, Argana Basin, Morocco). Middle Triassic (Anisian-Ladinian) footprint assemblages come from the classical Buntsandstein localities (Solling-Roet formations) in Germany, and equivalents of the Muschelkalk (Grafenwöhr-, Eschenbach- Vossenveld formations, Grés de Lyonnais) in Germany, The Netherlands and France, coeval deposits of northern Italy, from the Upper Moenkopi Formation/Group of Arizona and Utah, from the Timezgadiouine Formation of the Argana Basin, Morocco and from the Guanling Formation of China. Upper Triassic (Carnian-Rhaetian) footprint assemblages are found in Europe (Keuper and other deposits in Germany, France, Spain, Italy, Sweden, Poland), North America (Chinle Group, Newark Supergroup), South America (different units in Argentina, Bolivia, Peru, Brazil), East Greenland (Fleming Fjord Group), North Africa (Timezgadiouine Formation, Argana Basin, Morocco), southern Africa (Lower Elliot Formation, Lesotho), different continental deposits of China and in Australia (Sydney Basin, Queensland).
Biostratigraphically, Triassic tetrapod footprints have been used to define five biochrons:
(1) Dicynodont tracks (Induan-Olenekian), (2) Protochirotherium (Olenekian), (3) Chirotherium barthii (early Anisian), (4) Atreipus-Grallator (late Anisian-Ladinian), and (5) Brachychirotherium (Carnian–Rhaetian). Tetrapod footprint assemblages from the Triassic give insight into the development of early Mesozoic terrestrial vertebrate communities. Innovations in the locomotor apparatus and gait, such as the evolution of the erect stance and bipedality, which partly began during the Permian, were perfected during the Triassic and were the likely key to the rise to dominance of the archosaurs.
DESCRIPTION Comprehensive in detail and worldwide in scope, Chirotheres is the definitive compendium of what is known about the five-toed footprints of Triassic archosaurs, ancestors of the crocodiles. Sandstone slabs with extensive trackways have been known for almost two centuries and are highlights in museum exhibits around the globe. These trackways provide direct insight into the locomotion and behavior of the fascinating reptiles that made these tracks, and, together with known skeletons, they allow a richer reconstruction of chirothere lifestyle than is possible from bones alone. Written by expert researchers in the fields of vertebrate ichnology, vertebrate paleontology, and scientific illustration, Chirotheres explores the various facets of chirothere research including the history of their study, footprint formation and preservation, the bone record, the environment and lifestyle of chirotheres, and finally, their disappearance at the end of the Triassic. Chirotheres also features a global compendium of track collections with chirothere material, including specimen numbers, detailed phylogenetic definitions of track makers, and extensive measurements from key chirothere tracks and trackways. It represents an invaluable resource of anyone interested in these ancient animals. Powered by TCPDF (www.tcpdf.org) To order this book visit Herman B Wells Library, 1320 E 10th Street, Bloomington, Indiana 47405 • iuporder@iupress.org
3D digitisation of surfaces became a standard procedure in ichnology in recent years. 3D models allow not only for the digital preservation of vulnerable ichnological records, but also for the illustration, qualitative description, and quantitative analysis of the fossils. Here we discuss how to obtain photographs for photogrammetry, to generate, scale, and orient the models, and to extract visualisations, measurements, and coordinates for data analysis. Different visualisation approaches are discussed and compared, including widely used techniques such as orthophotos, height maps, and contour maps, as well as rarely used yet promising methods such as low-angled shaded reliefs, surface inclination plots, ambient occlusion, and radiance scaling. These techniques may filter or enhance different properties of the model surface such as colour information, elevation, edges and slopes, 3D morphology, and specific features such as convexities or concavities, and will often reveal additional detail. Furthermore, an approach is presented to automatically calculate trackway parameters based on coordinates collected from the model visualisations. All discussed steps can be performed with free and open-source software, and we provide detailed software instructions. We argue that digital ichnology, when combined with sedimentological data of the site, can be equally or more effective and comprehensive as traditional ichnological fieldwork. A digitalização 3D de superfícies tornou-se um procedimento padrão em icnologia em anos recentes. Os modelos 3D permitem não só a preservação digital de registos icnológicos vulneráveis, mas também a ilustração, descrição qualitativa, e análise quantitativa dos fósseis. Aqui discutimos como obter fotografias para fotogrametria, criar, medir, e orientar os modelos, e extrair visualizações, medidas, e coordenadas para análise de dados. Diferentes abordagens de visualização são discutidas e comparadas, incluindo técnicas amplamente utilizadas como ortofotos, mapas de altura, e mapas de contorno, assim como métodos raramente usados embora promissores, como relevos sombreados de baixo ângulo, projecções de inclinação de superfície, oclusão de ambiente, e escala de radiância. Estas técnicas podem filtrar ou melhorar diferentes propriedades da superfície do modelo como informação de cor, elevação, limites e declives, morfologia 3D, e características específicas como convexidades ou concavidades, e revelam regularmente detalhes adicionais. Além disso, uma abordagem é apresentada para automaticamente calcular parâmetros de trilhos baseados em coordenadas recolhidas de visualizações de modelos. Todos os passos discutidos podem ser efectuados com software livre e aberto, e fornecemos instruções detalhadas do software. Argumentamos que a icnologia digital, quando combinada com dados sedimentológicos da jazida, podem ser igualmente ou ainda mais eficazes e detalhadas que trabalho de campo icnológico tradicional. How to cite this paper: Lallensack, J. N., M. Buchwitz, and A. Romillo. 2022. Photogrammetry in Ichnology: 3D model generation, visualisation, and data extraction. Journal of Paleontological Techniques 22: 1-18.
As part of a 1930s public works project, two specimens revealing a total of ~20 tracks, preserved as natural casts, were collected and built into the interior walls of what was then the Fruita Museum in western Colorado. Based on our knowledge of the regional tetrapod ichnofaunas we are able to designate these as a "Triassic specimen" and a "Jurassic specimen" which invite description in detail. Although the geographical origin of both track assemblages is unknown, the tracks are well preserved, in partial trackways and can be identified with some confidence. Thus, one specimen is shown to reveal the ichnogenus Procolophonichnium and an indeterminate, probable therapsid track which marks the specimen as almost certainly from the Lower-Middle Triassic Moenkopi Formation. The other specimen reveals tridactyl tracks here identified as Anomoepus with associated traces which suggest it originated from the Upper Jurassic Morrison Formation.
Triassic tetrapod footprints have been studied since the 1830s and are now known from all of the World’s continents. An ichnotaxonomic revision of all Triassic tetrapod ichnogenera recognizes 34 valid ichnogenera: Anshunpes, Apatopus, Atreipus, Banisterobates, Batrachichnus, Batrachopus, Brachychirotherium, Brasilichnium, Capitosauroides, Characichnos, Chelonipus, Chirotherium, Dicynodontipus, Dikoposichnus, Dolomitipes, Eoanomoepus, Eosauropus, Eubrontes, Evazoum, Grallator, Gwyneddichnium, Isochirotherium, Pengxianpus, Pentasauropus, Procolophonichnium, Protochirotherium, Protorodactylus, Pseudotetrasauropus, Rhynchosauroides, Rotodactylus, Synaptichnium, Tetrasauropus, Therapsipus and Trisauropodiscus. A comprehensive, ichnospecies-level ichnotaxonomic revision of chirotheriid footprints recognizes the following ichnospecies as valid: Brachychirotherium hassfurtense, B. thuringiacum, B. parvum, Chirotherium barthii, C. ferox, C. ladinicum, C. postchirotherioides, C. ischigualastianum, C. rex, C. sickleri, Isochirotherium soergeli, I. herculis, I. coltoni, I. lomasi, I. marshalli, I. coureli, I. felenci, Protochirotherium wolfhagense, P. hauboldi, Synaptichnium pseudosuchoides, S. diabloense, S. cameronense and S. kotanskii. A comprehensive review of the geographic and stratigraphic distribution of Triassic footprints identifies five tetrapod biochrons of Triassic age, mostly based on archosaur footprint ichnotaxa: (1) Earliest Triassic dicynodont footprints of Lootsbergian (= latest Changshingian-Induan) age; (2) Protochirotherium in strata of Nonesian age (=Olenekian); (3) The appearance of Chirotherium barthii and C. sickleri, Rotodactylus, Isochirotherium and Synaptichnium (“Brachychirotherium”) roughly demarcates the Nonesian-Perovkan (late Olenekian-Anisian) transition; (4) The appearance of tridactyl footprints and quadrupedal to bipedal trackways of the Atreipus-Grallator type (“Coelurosaurichnus”) demarcates the late Perovkan-Berdyankian (= late Anisian-Ladinian); and (5) Brachychirotherium (sensu stricto) appears at the beginning of the Otischalkian (= early Carnian) and is a characteristic ichnotaxon of the Late Triassic. Triassic tetrapod footprint assemblages can be assigned to the five archetypal tetrapod footprint ichnofacies (Batrachichnus, Brontopodus, Grallator, Chelichnus and Characichnos) and encompass diverse ichnocoenoses. An ichnological perspective based on footprints on Triassic tetrapod evolution reaches the following conclusions: (1) the tetrapod-footprint record lends no support to identification of a mass extinction of tetrapods across the Permo-Triassic boundary; (2) the upright gait originated during the Permian but was employed by diverse taxa, many bipedal, during the Triassic; (3) dicynodont therapsids diminished during the Triassic from abundant in the Early Triassic, to extinct late in the Triassic, whereas cynodonts were much more abundant and diverse during the Triassic; (4) the oldest turtle fossils are Early Triassic footprints, which significantly predate the oldest turtle body fossils, which are of Late Triassic (Carnian) age; (5) the oldest dinosaur body fossils are of Late Triassic (Carnian) age, but some footprints of Middle Triassic age were plausibly made by dinosaurs; and (6) both the body fossil and footprint record indicate a prolonged interval of high extinction rates and low origination rates of tetrapods across the Triassic-Jurassic boundary, not a single mass extinction of tetrapods.
We describe a Middle Triassic tetrapod footprint assemblage from the Muschelkalk along the margin of the Germanic Basin. Twelve excavated footprint levels yielded the ichnogenera Synaptichnium, Isochirotherium, Chirotherium, Atreipus-Grallator, Rotodactylus, Gwyneddichnium, Rhynchosauroides, Procolophonichnium, therapsid footprints similar to Dicynodontipus, an undetermined chirotheriid with exceptionally large manus imprints and tetrapod swim traces. Track makers of the Muschelkalk assemblages were archosauromorphs and crown-group archosaurs and synapsids. The absence of mudcracks and the high diversity of tetrapods suggest a paleoenvironment with long-term availability of water and food resources.
Turtle (Testudines) tracks, Chelonipus torquatus, reported from the early Middle Triassic (Anisian) of
Germany, and Chelonipus isp. from the late Early Triassic (Spathian) of Wyoming and Utah, are the oldest
fossil evidence of turtles, but have been omitted in recent discussions of turtle origins. These tracks provide
significant clues as to how early the turtle Bauplan originated. Turtle trackways are quite distinctive: the
manus and pes form tracks nearly parallel to the midline and indicate an unusually wide gait in which the
trackway width is nearly equal to the stride length. These tracks do not fit what would be expected to be
made by Triassic Pappochelys or Odontochelys, a supposed prototurtle and an early turtle, respectively. In
contrast, these tracks are consistent with what would be expected from the Triassic turtles Proganochelys
and Palaeochersis. The features inferred to be present in Triassic turtle tracks support the notion that
Odontochelys is a derived aquatic branch of the turtle stem lineage rather than the ancestral state of
all turtles. Chelonipus also resembles the Permian track Pachypes dolomiticus, generally assigned to a
pareiasaur trackmaker. These revelations highlight the need to consider all available evidence regarding
turtle origins, rather than just the body fossils.
Autochthonous Triassic sediments of the Vieux Emosson Formation near Lac d’Emosson, southwestern Switzerland, have yielded assemblages with abundant archosaur footprints that are assigned to chirotheriids based on pentadactyl pes and manus imprints with characteristic digit proportions. Tridactyl footprints formerly considered as those of dinosaurs are identified as incomplete extramorphological variants of chirotheriids. Recently discovered new sites, including a surface with about 1500 imprints, permit re-evaluation of ichnotaxonomy and modes of preservation. Most common are oval to circular impressions arranged in an “hourglass-like” shape, corresponding to pes-manus couples. Sediment displacement rims indicate the presence of true tracks rather than undertracks. A few well-preserved footprints with distinct digit traces allow closer assignments. Several chirotheriid ichnotaxa are present with Chirotherium barthii, ?Chirotherium sickleri, Isochirotherium herculis, Chirotheriidae cf. Isochirotherium isp. and indeterminate forms. This corresponds with characteristic assemblages from the Buntsandstein of the Germanic Basin. In the study area, the Vieux Emosson Formation is an up to 10 m thick fining-upward sequence with conglomerates, rippled sandstones, siltstones and mudstones and occasionally carbonate nodules. Sedimentological features such as high relief erosion, immature sediments, erosionally truncated metre-scale fining-upward sequences, palaeosols and unidirectional palaeocurrents clearly prove a fluvial depositional environment with sediment transport towards the northwest and the Germanic Basin. This contrasts with former assumptions of a coastal marine environment and a south-facing transport towards the Tethys. The footprints occur in the coarser lower portion of the sequence that is interpreted as a shallow braided river. From Obersand in the eastern Swiss Alps, a surface in dolomitic limestone (Röti Dolomite) is re-examined. The footprints are identified as Chirotherium barthii and were impressed in a carbonate tidal flat environment. Biostratigraphically, the occurrence of characteristic Buntsandstein assemblages with Chirotherium barthii supports an Anisian age of both locations.
An assemblage of reptile footprints from the abandoned Pomona Terra-cotta and the active Boren quarries in the middle Pekin Formation of the Sanford subbasin of the Deep River basin is the oldest track faunule recognized to date in strate of Late Triassic age in Eastern North America. The most common taxon is a possibly new genus of pentadactyl ichnite similar to, but distinct from, Brachychirotherium. It may lack manus impressions, has a strong tendency to be functionally tridactyl, and has an extremely shallow digit V impression. At least one track is over 30 cm in length. Also present is the quadrupedal, probably phytosaurian ichnite Apatopus lineatus, based on a trackway, and several small (<15 cm) bipedal and tridactyl forms that are probably dinosaurian. Other more poorly preserved forms are present. Apart from Apatopus, none of the tracks fit into recognized Newark ichnotaxa. The age of this track assemblage is early Tuvalian (early Late Carnian of the Late Triassic), based on associated tetrapod skeletal and macro- and micro-floral remains. This middle Pekin footprint assemblage is thus distinctly different, and older than all other Newark Supergroup footprint assemblages. It is important because it represents a transitional stage between the well known Middle Triassic assemblages and the more typically Newarkian Late Triassic assemblages. The apparently dinosaurian ichnites from this horizon are therefore arguably among the oldest in the world.
Two new cyclotosaurid species are described from the Moenkopi Formation of northern Arizona. Eocyclotosaurus wellesi n. sp. is a long- and slender-snouted heylerosaurine, represented by numerous specimens of various sizes. In addition to the skull roof and palate, parts of the braincase and mandible are described. During ontogeny the snout and interpterygoid vacuities become continuously broader. Quasicyclotosaurus campi n.g.n.sp. is a short- and broad-headed cyclotosaurid similar in many aspects to Carnian Cyclotosaurus, but with unique derived features not shared by other capitosauroids, notably a very short basicranium, a medially separated anterior palatal window, and an anteriorly elongated and stout palatine ramus of the pterygoid.
Every fall since 1950, the New Mexico Geological Society (NMGS) has held an annual Fall Field Conference that explores some region of New Mexico (or surrounding states). Always well attended, these conferences provide a guidebook to participants. Besides detailed road logs, the guidebooks contain many well written, edited, and peer-reviewed geoscience papers. These books have set the national standard for geologic guidebooks and are an essential geologic reference for anyone working in or around New Mexico. Free Downloads NMGS has decided to make peer-reviewed papers from our Fall Field Conference guidebooks available for free download. Non-members will have access to guidebook papers two years after publication. Members have access to all papers. This is in keeping with our mission of promoting interest, research, and cooperation regarding geology in New Mexico. However, guidebook sales represent a significant proportion of our operating budget. Therefore, only research papers are available for download. Road logs, mini-papers, maps, stratigraphic charts, and other selected content are available only in the printed guidebooks.
Triassic vertebrate tracks are known from the beginning of the 19th century and have a worldwide distribution. Several Triassic track ichnoassemblages and ichnotaxa have a restricted stratigraphic range and are useful in biochronology and biostratigraphy. The record of Triassic tracks in the Iberian Peninsula has gone almost unnoticed although more than 25 localities have been described since 1897. In one of these localities, the naturalist Longinos Navás described the ichnotaxon Chirotherium ibericus in 1906.The vertebrate tracks are in two sandy slabs from the Anisian (Middle Triassic) of the Moncayo massif (Zaragoza, Spain). In a recent revision, new, previously undescribed vertebrate tracks have been identified. The tracks considered to be C. ibericus as well as other tracks with the same morphology from both slabs have been classified as Chirotherium barthii. The rest of the tracks have been assigned to Chirotheriidae indet., Rhynchosauroides isp. and undetermined material. This new identification of C. barthii at the Navás site adds new data to the Iberian record of this ichnotaxon, which is characterized by the small size of the tracks when compared with the main occurrences of this ichnotaxon elsewhere. As at the Navás tracksite, the Anisian C. barthii-Rhynchosauroides ichnoassemblage has been found in other coeval localities in Iberia and worldwide. This ichnoassemblage belongs to the upper Olenekian-lower Anisian interval according to previous biochronological proposals. Analysis of the Triassic Iberian record of tetrapod tracks is uneven in terms of abundance over time. From the earliest Triassic to the latest Lower Triassic the record is very scarce, with Rhynchosauroides being the only known ichnotaxon. Rhynchosauroides covers a wide temporal range and gives poor information for biochronology. The record from the uppermost Lower Triassic to the Middle Triassic is abundant. The highest ichnodiversity has been reported for the Anisian with an assemblage composed of Dicynodontipus, Procolophonichnium, Rhynchosauroides, Rotodactylus, Chirotherium, Isochirotherium, Coelurosaurichnus and Paratrisauropus. The Iberian track record from the Anisian is coherent with the How to cite this article Díaz-Martínez et al. (2015), A reappraisal of the Middle Triassic chirotheriid Chirotherium ibericus Navás , 1906 (Iberian Range NE Spain), with comments on the Triassic tetrapod track biochronology of the Iberian Peninsula. PeerJ 3:e1044
A remarkable Middle Triassic (Pelsonian, Anisian) fossil track site at Bernburg in Central Germany permits reconstruction of a tetrapod fauna at the point of recovery when early poposaur quadruped dinosaurs diversificated globally. The site has yielded numerous tetrapod and thousands of arthropod horseshoecrab tracks from several levels in intertidal biolaminites with intercalated storm and seismic-influenced carbonates. The tetrapod tracks, Procolophonichnium, Rhynchosauroides, Chirotherium, and Isochirotherium, are assigned to smaller Archosauromorpha and large Archosauria. The largest chirotheroid tracks Isochirotherium herculis (Egerton in Proc Geol Soc London 3:14-15, 1838) reach up to 350-mm-long pes sizes and 120-mm-long manus imprints. Those were most probably made by a 5-m-long poposauroid archosaur like Arizonasaurus, based on matching skeleton anatomy and trackways including a new three-dimensional model of those giants in locomotion. A first German poposauroid bone record is added herein with a scapula from shallow marine carbonates of similar Pelsonian ages. These crurotarsan archosaurs were at the top of their food chains globally, and fed most probably on smaller tetrapods (Hescheleria, Macrocnemus), the latter also represented well by long behavioural escaping Rhynchosauroides trackways. The smaller reptiles may have fed especially on “Millions” of horseshoecrab eggs in those arthropod reproduction seasons in the intertidal carbonate mud flats. Such tidal flats and sabkhas extended over hundreds of square kilometres surrounding the Germanic Basin in Central Europe in the Middle Triassic, representing a drastic change in the palaeoenvironment of central Pangaea, and a possible trigger for continuing diversification of archosauromorphs and eventually dinosaurs. The horseshoecrab reproduction seasons seem to have caused a food chain reaction along the southern Pangaean (northern Tethys) coast in carbonate mud flats between Northern America, Africa, Europe and China, with possibly long-distance migrations of poposauroids such as Arizonasaurus, whose bones were found in terrestrial to shallow marine carbonate deposits in terrest to coastal context.
Fossil tetrapod swim tracks have been reported from deposits throughout the world, ranging in age from the Carboniferous (Mississippian) to the Neogene (Pleistocene). A normalized analysis of these occurrences demonstrates that lower Triassic strata contain an anomalously high number of occurrences. Lower Triassic swim tracks also tend to be better preserved, showing exceptionally detailed features such as scale striae and crescent-shaped claw margins. Preservation of these features required a firm and semicohesive substrate in order to maintain track detail before and after burial. Swim-track localities from the lower Triassic Moenkopi Formation in Utah (USA) are characterized by sedimentary and trace fossil features that demonstrate the widespread development and persistence of firmground substrates in a large delta plain complex. Within this delta, complex low-diversity invertebrate trace fossil assemblages consist of locally high densities of diminutive, millimeter-scale traces characteristic of stressed brackish-water faunas. We suggest that the depauperate infauna characteristic of such environments was repressed due to delayed biotic recovery following the end-Permian mass extinction, resulting in extremely low intensities of bioturbation. Lack of biogenic mixing promoted semiconsolidation of dewatered mud substrates and the widespread production and persistence of firmgrounds capable of recording and maintaining swim tracks. Thus a combination of factors, unique to the Early Triassic, increased the preservation potential of detailed swim tracks: (1) depositional environments that promoted the production of firmground substrates, (2) delayed ecologic recovery resulting in the lack of well-bioturbated sediment, and (3) the swimming behavior of various Early Triassic tetrapods.
Although skeletal remains attributed to reptiles are rare in the Lower-Middle Triassic Moenkopi Formation of western North America, this formation does preserve a medium- to high-diversity assemblage of reptile tracks. This assemblage commonly includes swipe marks made by buoyant or partially buoyant tetrapods interpreted as reptile swim tracks. In south-central Utah swim tracks occur exclusively within the Torrey Member and are more abundant and better preserved there than in other areas throughout Utah. The Torrey Member is interpreted as representing deposition within a large delta complex, and the stratigraphic and ichnologic observations reported here support that interpretation. Stratigraphic sections measured at two swim track sites in Glen Canyon National Recreation Area show evidence of deposition within interdistributary channels and bays filled by crevasse splay deposits. These environments most likely provided ideal conditions for the development of firmground substrates that greatly increased the preservation potential of swim tracks. Due to the paucity of skeletal remains from units of this age in western North America, these tracks and the paleoenvironmental controls on their preservation provide valuable insights into the paleoecology of Early-Middle Triassic reptiles.
The Cynognathus Assemblage Zone (AZ) has been recognized for more than 100 yr and is one of the most durable tetrapod biostratigraphic concepts of the Triassic. Long treated as a single biostratigraphic unit, the Cynognathus AZ is now divided into three subzones (in ascending order), A, B and C. The South African Cynognathus AZ can be correlated across Pangea to tetrapod assemblages in Algeria, and Zambia. Various index taxa found in the subzones of the Cynognathus AZ in the Karoo basin provide multiple and reinforcing correlations, and independent age constraints combined with marine records of Parotosuchus associated with ammonoids indicate that subzone A is of Olenekian age, primarily Spathian, but perhaps as old as part or all of the Smithian. The early Anisian age of subzone B lacks robust support and is largely based on its stratigraphic position in the Karoo basin between late Olenekian (subzone A) and late Anisian (subzone C) assemblages. In China a subzone B assemblage of the lower Ermay-ing Formation is overlain by a late Anisian assemblage of the upper Ermaying Formation correlative to sub-zone C. The Russian Eryosuchus fauna, which is very likely of Anisian age, is at least in part correlative with subzone B, and palynostratigraphy in Australia also indicates an Anisian age for strata (Ashfield Slate) that contain subzone B and C tetrapods. Correlation of subzone C to the later Anisian is primarily supported by a radioisotopic age from China that indicates a subzone C tetrapod assemblage is ~ 243 Ma. The beginning of Perovkan time is close to the beginning of the Anisian, so the Nonesian is the time equivalent to subzone A, and subzones B and C are of Perovkan age. Nevertheless, how close the base of subzone B of the Cynognathus AZ may be to the base of the Anisian is not clear, and a stronger basis is needed to identify the beginning of the Anisian and the beginning of the Perovkan land-vertebrate faunachron in the time interval represented by subzone B of the Cynognathus AZ.
The Middle Triassic is a key time span for understanding the evolution of archosaurs and the rise of Dinosauromorpha. A further source of information on this issue may be provided by the study of tetrapod footprints. We revise the tetrapod ichnoassociation of the Quarziti del Monte Serra Formation (Verrucano Group, Monti Pisani, Italy) and identify the following ichnotaxa: cf. Atreipus isp. (dinosauromorph), Chirotherium barthii, C. gallicum (archosauriforms), Rotodactylus isp. and Synaptichnium pseudosuchoides (archosauromorphs), Rhynchosauroides cf. palmatus (neodiapsid), cf. Circapalmichnus isp. and Procolophonichnium haarmuehlensis (therapsids). The ichnoassemblage is diverse and dominated by Rhynchosauroides tracks in the coastal pond deposits and non-diverse and dominated by archosaur tracks in the coastal sandflat deposits. Bivalve biostratigraphy supports the Ladinian age of the Quarziti del Monte Serra Formation inferred by the tetrapod ichnoassociation. The stratigraphically oldest occurrences of Atreipus from Italy, France, Morocco and Germany are likely Ladinian, which highlights a wide dispersal of dinosauromorphs as early as the Middle Triassic.
Tetrapod ichnology is a powerful tool to reconstruct the faunal composition of Middle Triassic ecosystems. However, reconstructions based on a single palaeoenvironment provide an incomplete and impoverished picture of the actual palaeodiversity. In this paper, we analyse Middle Triassic tetrapod ichnoassociations from the detrital Muschelkalk facies of the Catalan Basin of northeast Spain, ranging from terrestrial to coastal settings. We identified two main tetrapod ichnoassociations, preserved in two different palaeoenvironments, comprising the following ichnogenera and morphotypes: Procolophonichnium, Chelonipus, Rhynchosauroides, Rotodactylus, Chirotherium, Isochirotherium, Sphingopus, and indeterminate chirotheriids. We also statistically analyse a database of all known Middle Triassic tetrapod footprint localities worldwide; this database includes, for each track locality, the precise age, the palaeoenvironment and the presence/absence of ichnotaxa. Our results on the composition of ichnofauna within the palaeoenvironments of the Catalan Basin are integrated into this database. This approach allows us to revisit the palaeoenvironmental bias linked to the marine transgression that affected the Western Tethys region. Tetrapod ichnoassociations reveal the following palaeoenvironmental patterns: (1) in coastal settings, ichnoassociations are Rhynchosauroides-dominated and diversity is relatively low; (2) in terrestrial settings and those with less marine influences, ichnoassociations are non-Rhynchosauroides-dominated, usually characterised by more abundant chirotheriid tracks and, generally, a higher track diversity. The correlation between tetrapod ichnoassociations and sedimentary facies reveals how palaeoenvironmental constraints influenced faunal assemblages, especially those of the Middle Triassic of the Western Tethys region. Ichnoassociations allow the ecological response of tetrapod faunas to the environmental changes to be inferred for this critical time interval. Marine transgressions strongly influenced tetrapod ecosystems: environmental conditions were key for the faunal recovery in the aftermath of the end-Permian extinction, with the settlement of the so-called modern faunas and the rise of the dinosaur lineage.
Triassic temnospondyl amphibian tracks are relatively rare, in contrast with the body fossil record. Herein we report temnospondyl tracks from the base of the Anthrakonitbank carbonate bed, within the upper Middle Triassic Lower Keuper succession (Erfurt Formation) in the Vellberg Fossil-Lagerstätte of southern Germany. The sedimentary succession comprises restricted marine deposits, and the track-bearing layer includes microbial mats covering thin bone-beds. The ichnological material includes >20 footprints, four of which are arranged in a trackway, and all footprints comprise manus impressions with no pes preserved. The combination of characters, such as tetradactyl clawless manus impressions, relative digit length and angulation, and trackway with low pace angulation, are different from any known tetrapod ichnotaxon. While the scarcity of material precludes a confident ichnotaxonomy, comparison with the autopodia in the body fossil record suggests capitosaur stereospondyls as the most probable trackmakers. Ichnological and sedimentological features indicate that the trackmakers displayed a walking-swimming locomotion, with a sprawling posture, only touching the substrate with the forelimbs, as seen in present-day swimming crocodiles. The Vellberg tetrapod tracks reported here contribute to our knowledge of the Triassic ichnological record, as well as the life style and habitats of temnospondyls.
Nonmarine biostratigraphic/biochronologic schemes have been created for all or parts of the late Carboniferous–Middle Triassic using palynomorphs, megafossil plants, conchostracans, blattoid insects, tetrapod footprints and tetrapod body fossils, and these provide varied temporal resolution. Cross correlation of the nonmarine biochronologies to the Standard Global Chronostratigraphic Scale has been achieved in some parts of the late Carboniferous–Middle Triassic in locations where nonmarine and marine strata are intercalated, the nonmarine strata produce biochronologically significant fossils and the marine strata yield fusulinids, conodonts and/or ammonoids. Other cross correlations have been aided by magnetostratigraphy, chemostratigraphy and a growing database of radioisotopic ages. A synthetic nonmarine biochronology for the late Carboniferous–Middle Triassic based on all available nonmarine index fossils, integrated with the Standard Global Chronostratigraphic Scale, is presented here. The focus is on the nonmarine biostratigraphy/biochronology of blattoid insects, conchostracans, branchiosaurid amphibians, tetrapod footprints and tetrapod body fossils within the biochronological framework of land-vertebrate faunachrons. Correlation to the Standard Global Chronostratigraphic Scale presented here is divided into seven time intervals: Pennsylvanian, Carboniferous–Permian boundary, Cisuralian, Guadalupian, Lopingian, Permian–Triassic boundary and Early to Middle Triassic. The insects, conchostracans and branchiosaurs provide robust nonmarine correlations in the Pennsylvanian–Cisuralian, and the footprints and tetrapod body fossils provide robust correlations of varied precision within the entire Pennsylvanian–Middle Triassic. Radioisotopic ages are currently the strongest basis for cross correlation of the nonmarine biostratigraphy/biochronology to the Standard Global Chronostratigraphic Scale, particularly for the Pennsylvanian–Cisuralian. Chemostratigraphy and magnetostratigraphy thus far provide only limited links of nomarine and marine chronologies. Improvements in the nonmarine-marine correlations of late Paleozoic–Triassic Pangea require better alpha taxonomy and stratigraphic precision for the nonmarine fossil record integrated with more reliable radioisotopic ages and more extensive chemostratigraphic and magnetostratigraphic datasets.
The Middle Triassic (Anisian) Guanling Formation in Yunnan and Guizhou provinces, southwestern China, is well-known for its marine-reptile fauna with numerous well-preserved skeletons. Tetrapod footprints from this unit have been reported of both terrestrial and marine forms documenting a marginal marine environment in the eastern Tethys region. In particular Chirotherium barthii, an ichnospecies that is characteristic of the Middle Triassic (Anisian), was formerly described from the Guanling Formation of Guizhou Province. Recently chirotheriid tracks were also reported from deposits of this unit in Yunnan Province. Here we provide the first detailed documentation of this tracksite. Furthermore, we assign these trackways to the ichnospecies Chirotherium barthii, based on identical features in footprint morphology. Additionally, from the same surface, we describe the first tracks and trackways of the lacertoid ichnogenus Rhynchosauroides from the Asian continent. Trackmakers of C. barthii are non archosaurian archosauriforms or members of the archosaur crown-group, while Rhynchosauroides can be attributed either to lepidosaur-omorph or archosauromorph diapsids. The environment was a coastal area along the eastern Tethys, with marine, semi-aquatic and terrestrial tetrapods leaving their footprints in the carbonatic sediment of mudflats and lagoons when searching for food, that possibly consisted of small marine invertebrates or the small lacertoid forms being the prey of the larger archosaurs. ARTICLE HISTORY
The morphology of fossil footprints is the basis of vertebrate footprint ichnology. However, the processes acting during and after trace fossil registration which are responsible for the final morphology have never been precisely defined, resulting in a dearth of nomenclature. Therefore, we discuss the concepts of ichnotaphonomy, ichnostratinomy, taphonomy, biostratinomy, registration and diagenesis and describe the processes acting on footprint morphology. In order to evaluate the morphological quality of tetrapod footprints, we introduce the concept of morphological preservation, which is related to the morphological quality of footprints (M-preservation, acronym MP), and distinguish it from physical preservation (P-preservation, acronym PP), which characterizes whether or not a track is eliminated by taphonomic and diagenetic processes. M-preservation includes all the morphological features produced during and after track registration prior to its study, and may be divided into substages (ichnostratinomic, registrational, taphonomic, stratinomic, diagenetic). Moreover, we propose an updated numerical preservation scale for M-preservation. It ranges from 0.0 (worst preservation) to 3.0 (best preservation); intermediate values may be used and specific features may be indicated by letters. In vertebrate footprint ichnotaxonomy,
we regard the anatomy-consistent morphology and to a lesser extent the trackway pattern as the only acceptable ichnotaxobases. Only footprints showing a good morphological preservation (grade 2.0–3.0) are useful in ichnotaxonomy, whereas ichnotaxa based on poor morphological preservation (grade 0.0–1.5) are considered ichnotaphotaxa (nomina dubia) characterized by extramorphologies. We applied the preservation scale on examples from the Palaeozoic to the present time, including three ichnotaphotaxa and 18 anatomy-consistent ichnotaxa/morphotypes attributed to several vertebrate footprint producers. Results indicate the utility, feasibility and suitability of this method for the entire vertebrate footprint record in any lithofacies, strongly recommending its
use in future ichnotaxonomic studies.
Ichnology is the study of traces created in the substrate by living organisms. This is the first book to systematically cover basic concepts and applications in both paleobiology and sedimentology, bridging the gap between the two main facets of the field. It emphasizes the importance of understanding ecologic controls on benthic fauna distribution and the role of burrowing organisms in changing their environments. A detailed analysis of the ichnology of a range of depositional environments is presented using examples from the Precambrian to the recent, and the use of trace fossils in facies analysis and sequence stratigraphy is discussed. The potential for biogenic structures to provide valuable information and solve problems in a wide range of fields is also highlighted. An invaluable resource for researchers and graduate students in paleontology, sedimentology and sequence stratigraphy, this book will also be of interest to industry professionals working in petroleum geoscience.
The Moenkopi formation of Triassic age is composed of a series of deposits that form a wedge thinning eastward from a maximum of about 2000 feet in western Utah and southern Nevada to the vanishing point along an irregular margin in western Colorado, northeastern Arizona, and western New Mexico. Partly marine and partly continental in the thick western sections, it is entirely continental in the east. Invertebrate faunas indicate that deposition began either during or preceding the middle of the Early Triassic (Meekoceras zone) and continued into late Early Triassic (Tirolites zone) and probably into Medial Triassic time. Vertebrate faunas also indicate an Early Triassic and probably, in part, a Medial Triassic age. Studies of the deposits indicate three major transgressions and three regressions across southern Utah and northern Arizona. Analysis of sedimentary rock types and original structures in them suggests a complex mixture of environments involved in the development of the formation: stream beds, lagoons, playas, flood plains or tidal flats, shallow sea floors, and others. Some types are clear cut and readily demonstrated; others are open to question. Evidence from flora, fauna, and sediments indicates a semiarid to arid climate. Except for uplift in the Uncompahgre region of Colorado indicated by conglomeratic beds in the Moenkopi near by, the entire region probably remained very low and flat during Moenkopi deposition.
The diverse depositional environments and rich fossil assemblages of the early Mesozoic Newark Supergroup of eastern North America can be subdivided into six broad environmental categories ranging from fault-scarp breccias in synsedimentary grabens developed directly along master boundary fault zones to deep-water zones of lakes. Each environmental category is characterized by its own range of taxa and modes of preservation. Environmental zones, except those directly caused by faulting, shifted laterally as lake levels rose and fell. Overt analogy between the lower trophic levels of aquatic ecosystems of modern lakes and those of the early Mesozoic is not appropriate. Diatoms were absent from the phytoplankton and large (0.3–1.0 cm) clam-shrimp comprised most of the zooplankton in Newark lakes, despite the abundant planktivorous fish.
Scoyenia and Ancorichnus are interpreted as feeding structures, although certain details of the feeding-burrowing mechanism remain conjectural. Known occurrences of such trace fossils indicate that the tracemakers preferred moist or wet nonmarine substrates, whether shallow aquatic deposits periodically exposed to air or low-lying subaerial deposits periodically inundated by water.-from Authors
Batrachotomus kupferzellensis is an upper Middle Triassic (Late Ladinian) rauisuchian archosaur. The postcranial skeleton of this species is well-represented by fossil material, including the holotype, from the localities of Kupferzell, Crailsheim and Vellberg-Eschenau in southern Germany, and is described here in detail for the first time. All postcranial elements are known except the interclavicle and parts of the carpus, manus, tarsus, pes and some osteoderm and axial elements. B. kupferzellensis is now one of the best-known rauisuchians and will be important in advancing understanding of the group's biology. A period of new anatomical and taxonomic work since 2000 has improved understanding of rauisuchians. Renewed effort in rauisuchian phylogenetics will benefit from these new data, but will also require a careful and detailed approach to character formulation.