Crocodile swim tracks from the latest Cretaceous of Europe

Recently discovered evidence of tracks in the continental beds of the Late Cretaceous Tremp Formation in the southern Pyrenees (NE Iberian Peninsula) has been identified as scratch marks made by buoyant crocodiles. The tracks are preserved in two distinct environments and substrates (marly limestones originating in a littoral mud flat and fine‐grained sandstones deposited in fluvial settings). Most of the crocodylian traces are ascribed to ichnogenus Characichnos, whereas a single plantigrade pes track is assigned to ichnogenus cf. Crocodylopodus. The crocodylian swim traces (Characichnos ichnofacies) found in the early and late Maastrichtian co‐occur with Brontopodus ichnofacies attributable to terrestrial tetrapods (titanosaur sauropods, cf. Brontopodus ichnogenus; and hadrosaurid ornithopods, Hadrosauropodus ichnogenus). Analysis of the tracks allows the interpretation of palaeoenvironmental settings and track production. Thus, in lagoonal environments, swim tracks of crocodylians were produced during the rise of the water level in successive tide cycles; in fluvial settings, the swim traces of crocodylians were produced within the channel at the low‐water stage. To date, there are no reports of Late Cretaceous crocodylian tracks in Europe, and the studied evidence represents the first and youngest track record of the group in the latest part of the Cretaceous (C29r) in this continent and probably in the world.     

Large Pelycosaur Footprints from the Lower Pennsylvanian of Alabama,USA

Relatively large tetrapod footprints from Lower Pennsylvanian strata of the Pottsville Formation in the Warrior basin coal field of Alabama were previously assigned to the ichnogenus Attenosaurus. However, three morphotypes are present, and we assign these tracks to Attenosaurus, a new ichnogenus (Alabamasauripus) and Dimetropus. Most of these tracks apparently were made by large pelycosaurs, for which there is no bone record older than Late Pennsylvanian.     

Oligocene Shorebird Footprints,Kandi, Ombilin Basin,Sumatra

Recent fieldwork in the Ombilin Basin of west-central Sumatra resulted in the discovery of two distinct types of avian footprints, both referable to the ichnogenus Aquatilavipes. The footprints were discovered in the Oligocene Sawahlunto Formation in a creek side outcrop near the Kandi Ombilin Mine. Aquatilavipes wallacei is a small species of Aquatilavipes (～ 19 mm wide; 27 mm long) with elongate third digits, wide total divarication angles (120–150°) and inwardly curved peripheral digits. Aquatilavipes ichnospecies A are also small traces (average 21 mm wide; 31 mm long) with elongate third digits and straight to slightly outwardly curved peripheral digits. These traces are similar in morphology to those of small modern shorebirds such as rails (Rallidae), sandpipers (Scolapacidae) or plovers (Charadriinae).

The Sawahlunto traces occur in very fine-grained to fine-grained sandstone characterized by low-relief current ripples, many of which exhibit mud-draping. A low diversity invertebrate trace fossil assemblage consisting of Arenicolites, Diplocraterion, Planolites, Monocraterion, Skolithos and Coenobichnus co-occurs with the bird footprints. This succession is interpreted as intertidal sand flats. Probe and peck marks preserved on the same bedding planes as the bird footprints support the interpretation that these birds occupied the Kandi intertidal flats for foraging purposes.     

New localities of Late Eocene vertebrate footprints from the Tarom Mountains,Northwestern Iran

We document Late Eocene vertebrate footprints from the Tarom Mountains of Iran that represent a significant addition to the record of proboscidean and perissodactyl footprints. These footprints are from sandstones and tuffaceous sandstones of strata equivalent to the Kond Formation that overlie middle Eocene sedimentary rocks and are overlain by Oligocene volcanics. The footprints are preserved at 16 tracksites from 10 distinct stratigraphic levels. The mammal footprints include the oldest known proboscidean tracks, assigned to Proboscipeda enigmatica Panin & Avram and to cf. Proboscipeda isp. Evident perissodactyl tracks are common, tridactyl footprints with distinct digit shapes and proportions assigned to the new ichnogenus and ichnospecies Moropopus elongatus. Footprints of small, hopping, rodent-like mammals are identified as Musaltipes taromi new ichnospecies. Other mammal footprints from the Tarom tracksites are indeterminate, and bird footprints are assigned to Avipeda isp. The Tarom tracksites document the oldest record of proboscidean footprints, and this indicates that proboscideans had reached the northern shore of Tethys by Late Eocene time. The abundance and distinctiveness of the Tarom perissodactyl tracks mirrors the abundance and diversity of moropomorph perissodactyls during the Middle-Late Eocene. The Tarom tracksites are the most extensive record of Eocene vertebrate footprints known from Iran.

http://zoobank.org/urn:lsid:zoobank.org:pub:F430F9DB-728F-4162-9791-DC2A5CC5ED43     

First Thyreophoran Type Tracks from the Middle Jurassic Chuanjie Formation of Yunnan Province,China

Two tridactyl footprints from the Chuanjie Formation (Middle Jurassic) of Yunnan Province, China are morphological characteristics of thyreophoran tracks. They show some similarities to Shenmuichnus, known from the Early Jurassic strata of both Shaanxi and Yunnan provinces, but are somewhat larger, thereby resembling the ichnogenus Stegopodus. Based on their general morphology and size being congruent with this ichnogenus, they are tentatively assigned here to cf. Stegopodus. This is the fourth report of large ornithischian (probably thyreophoran) tracks from the Lower-Middle Jurassic of China that indicates relatively large trackmakers that were likely to be taxonomically distinct from much smaller and gracile Anomoepus trackmakers, also of ornithischian affinity. The larger tracks indicate a hitherto unreported abundance, size range and diversity of track types attributed to this group. The parallel orientation of the two best preserved trackways may indicate gregariousness.     

Crocodylian Tracks from Lower Oligocene Flysch deposits of the Barail Group,Manipur, India

A marine tidal delta siltstone from Gelmon locality in Northeast India preserved three crocodylian footprints and an elongate depression that appears to be a tail drag mark. Similar drag marks occur in nearby bedding surfaces. The discovery of crocodylian tracks from the basal part of Laisong Formation, Barail Group (Late Eocene–Early Oligocene age) of Manipur, India is noteworthy because of the age and the geographic location. Crocodylian tracks are rare in Cenozoic formations and they have not previously been reported from Asia. The footprints are herein named as a new ichnogenus and ichnospecies, Indosuchipes manipurensis.     

A Diverse Dinosaur-Bird Footprint Assemblage from the Lance Formation,Upper Cretaceous,Eastern Wyoming: Implications for Ichnotaxonomy

A diverse assemblage of dinosaur and bird tracks from Niobrara County, Wyoming, represents the first vertebrate ichnofauna reported from the bone-rich Lance Formation (Maastrichtian, Upper Cretaceous). The ichnofauna includes a hadrosaur track with skin impressions; three theropod track types, including the tetradactyl track Saurexallopus zerbsti (ichnosp. nov.); a tridactyl dinosaur footprint with a fusiform digit III; possible Tyrannosaurus tracks; four distinctive avian ichnites; and invertebrate traces. The footprints are generally well-preserved and so offer a unique insight into the ecology of a small river valley during the Maastrichtian.

Saurexallopus zerbsti ichnosp. nov. from the Lance is similar to Saurexallopus lovei recently reported from the Maastrichtian, Harebell Formation, of northwestern Wyoming, but is represented by much better material, facilitating amendment of the ichnogenus. Skeletal equivalents for Saurexallopus are not currently known. Similarly, the tridactyl track with fusiform digit III is similar to footprints reported from the coeval Laramie Formation of Colorado and may also be similar to ichnogenus Ornithomimipus from the Edmonton Group of Alberta (though not necessarily of ornithomimid affinity). The hadrosaurian track with the skin impression is reminiscent of a similar ichnite reported from the Maastrichtian, St. Mary River Formation in Alberta, which is herein named Hadrosauropodus langstoni as part of a reassessment of Cretaceous ornithopod track ichnotaxonomy. Such correlations demonstrate the utility of tracks for local or regional biostratigraphy (palichnostratigraphy) in western North America. It is also clear that tracks add to our knowledge of the composition and distribution of dinosaurian and avian components of Maastrichtian faunas. In particular the bird tracks indicate a diversity of at least four species, one of which was a semi-palmate form, hitherto unknown in the ichnological record and named Sarjeantichnus semipalmatus.     

The Tetrapod Ichnogenus Protochirotherium Fichter and Kunz 2004, a Characteristic Early Triassic Morphotype of Central Pangea

Early Triassic chirotherian footprint assemblages from Poland, Germany, and Morocco are important for understanding archosaur evolution in the aftermath of the Permian-Triassic crisis. However, their ichnotaxonomy is confusing because various authors have interpreted their diversity differently. After an analysis and ichnotaxonomic re-assessment, the presence of the ichnogenera Brachychirotherium, Isochirotherium, and Chirotherium in these assemblages is not supported. Distant similarities with these ichnotaxa are functions of extra morphological variation and substrate-related factors. Instead, Early Triassic chirotherian footprints described under these names are assigned here to the ichnogenus Protochirotherium and to a more slender morphotype identified as Synaptichnium. In particular, Protochirotherium appears to be more widely distributed in central Pangea as a characteristic morphotype reflecting a distinct stage in archosaur evolution. Trackmakers were nonarchosaurian archosauriforms or, alternatively, stem-group crocodylians. Morphologically and temporally these footprints match the hypothetical ancestor of the Chirotherium barthii trackmaker. Chirotherium barthii appears by the beginning of the Middle Triassic. Because of its restricted stratigraphic range, and its wider distribution in central Pangea, Protochirotherium also has biostratigraphic significance for this region and can be considered as an indicator of Early Triassic-aged strata.     

Sauropod and Small Theropod Tracks from the Lower Jurassic Ziliujing Formation of Zigong City,Sichuan, China,with an Overview of Triassic–Jurassic Dinosaur Fossils and Footprints of the Sichuan Basin

A dinosaur footprint assemblage from the Lower Jurassic Ziliujing Formation of Zigong City, Sichuan, China, comprises about 300 tracks of small tridactyl theropods and large sauropods preserved as concave epireliefs (natural molds). The theropod footprints show similarities with both the ichnogenera Grallator and Jialingpus. Three different morphotypes are present, probably related to different substrate conditions and extramorphological variation. A peculiar preservational feature in a morphotype that reflects a gracile trackmaker with extremely slender digits, is the presence of a convex epirelief that occurs at the bottom of the concave digit impressions. It is possibly the result of sediment compaction underweight load when the pes penetrated the substrate, being a resistant residue during exhumation and weathering. The sauropod tracks belong to a trackway with eight imprints consisting of poorly preserved pes and manus tracks and a better preserved set, probably all undertracks. The narrow-gauge trackway pattern resembles the ichnogenus Parabrontopodus well known from the Jurassic but other features such as the minor heteropody are different. The assemblage enriches the dinosaur record from the famous Zigong locality and the evidence from the Lower Jurassic in this area that was restricted to a few skeletal remains and footprints. Furthermore it proves the presence of small theropods, whereas skeletons of the group, well- known from the Middle-Upper Jurassic of Zigong, are of medium to large size only. Remarkable is the dominance of saurischians in these assemblages, which is characteristic of Jurassic dinosaur communities whereas the Cretaceous record shows an increase of ornithopod groups. An overview of the dinosaur trace and body fossil record of the Sichuan Basin supports this view. The paleoenvironment can be designated as a low-latitude tropical freshwater lake as it is indicated by bivalve shells.     

The Mississippian Tetrapod Footprint Ichnogenus Palaeosauropus: Extramorphological Variation and Ichnotaxonomy

Palaeosauropus primaevus is a tetrapod footprint ichnotaxon first described from the Upper Mississippian (Visean) Mauch Chunk Formation near Pottsville, Pennsylvania, United States. Our relocation of the type locality and stratigraphic horizon of P. primaevus, a long-available but unstudied collection of tetrapod footprints from these strata, and our new collections allow a much fuller characterization of this ichnotaxon and the range of extramorphological variation encompassed by it. P. primaevus is characterized as the footprints of a quadruped with a pentadactyl pes and a tetradactyl manus, in which the pes frequently oversteps the manus and with which tail drags are common. In the manus, all digits are relatively broad and have rounded tips, digit III is longest, and digit IV is more widely separated from digit III than the other digits are from each other. The pes has five digits that are also wide and blunt-tipped, digit IV is longest, and digit V projects nearly laterally. P. primaevus is the track of a relatively large temnospondyl (～400 mm gleno-acetabular length) and documents the Mississippian presence of such large amphibians long before their body fossil record. Palaeosauropus also occurs in Mississippian strata in Indiana and is distinguished from the geologically younger but similar temnospondyl footprint ichnogenus Limnopus by its relatively narrower manus and pes that lack broad and rounded sole impressions.     

The first record of Anomoepus tracks from the Middle Jurassic of Henan Province,Central China

Small, gracile mostly tridactyl tracks from the Middle Jurassic of Henan Province represent the first example of the ichnogenus Anomoepus from this region. They represent a growing number of reports (at least eight) of this ichnogenus from the Jurassic of China. In conjunction with Changpeipus and Eubrontes, they appear characteristic of known global footprint biochrons. Anomoepus indicates the presence of ornithischian dinosaurs that are often scarce or unknown from skeletal remains in coeval deposits. When first discovered, these tracks were informally referred to as bird tracks. This interpretation reflects convergence between small Jurassic Anomoepus and avian theropod tracks that are hitherto known only from the Cretaceous and the Cenozoic. However, most Anomoepus are larger and more robust than any hitherto known Mesozoic avian tracks.     

The non-avian theropod track Jialingpus from the Cretaceous of the Ordos Basin,China, with a revision of the type material: Implications for ichnotaxonomy and trackmaker morphology

Deposits from the Ordos Basin of mid-western China are rich in body fossils and ichnofossils of Early Cretaceous vertebrates. Thousands of Early Cretaceous sauropod, theropod and bird tracks described since 1958 have been found at several localities in the basin. We report two new sites (Dijiaping and Bawangzhuang) in the Luohe Formation of the Ordos Basin, Shaanxi Province, which contain small theropod footprints that are here referred to the ichnogenus Jialingpus. The assignment is based on pad configurations including (1) the large metatarsophalangeal area positioned in line with the axis of digit III, (2) the subdivision of this part into a small pad behind digit II, which in some specimens is close to the general position of the hallux (digit I), and a large metatarsophalangeal pad behind digit IV, and (3) a distinct inter-pad space between metatarsophalangeal pads and proximal phalangeal pads of digits II and III. We re-describe the type material of the type ichnospecies Jialingpus yuechiensis from the Upper Jurassic Penglaizhen Formation of Sichuan Province, proposing a largely amended diagnosis for this ichnotaxon. The presence of a digit I trace in the holotype, indicating a relatively long hallux, and the large metatarsophalangeal area positioned in line with digit III distinguishes Jialingpus from the ichnogenus Grallator and similar tracks that all lack these features. The only difference between Jialingpus specimens from the Cretaceous of the Ordos Basin and those of the Jurassic Penglaizhen Formation is the larger digit divarication in the Cretaceous taxon. This is the fourth record of Jialingpus in China and the second in Cretaceous strata, with the first being those from the Huangyangquan locality in Xinjiang, China.     

Late Triassic Aetosaurs as the Trackmaker of the Tetrapod Footprint Ichnotaxon Brachychirotherium

Brachychirotherium is the common ichnogenus of Late Triassic chirothere footprints well known from western Europe, North America, Argentina and South Africa. Although it has long been agreed by most workers that the trackmaker of Brachychirotherium was a derived crurotarsan archosaur, the trackmaker has been identified as either a rauisuchian or an aetosaur, and some workers attribute it to a primitive crocodylomorph (sphenosuchian). New knowledge of the osteology of the manus and pes of a large aetosaur, Typothorax coccinarum, indicates a close correspondence between the manus and pes structure of aetosaurs and the morphology of Brachychirotherium. Furthermore, functional analysis of complete skeletons indicates aetosaurs plausibly placed their feet in the narrow gauge, nearly the overstepped walk characteristic of Brachychirotherium. Brachychirotherium and aetosaurs have matched distributions, that is, they were Pangea-wide during the Late Triassic. The manus and pes morphology of rauisuchians and early crocodylomorphs (sphenosuchians) deviate from Brachychirotherium footprint morphology in key features, thus excluding their identification as trackmakers. Aetosaurs made Brachychirotherium footprints.     

Amphibian Body Impressions from the Mississippian of Pennsylvania,USA

Temnocorpichnus isaacleai is a new ichnogenus and ichnospecies of temnospondyl amphibian body impression from the Mississippian (Visean) Mauch Chunk Formation of eastern Pennsylvania, United States. The shovel-shaped head, robust limbs, relatively short trunk and smooth integument diagnose the ichnotaxon and readily distinguish it from Hermundurichnus and Sauropleura, the only other named body impressions of Paleozoic tetrapods. Temnocorpichnus is a compound ichnogenus in which the footprint ichnogenus Batrachichnus is a behaviorally distinct component. The temnospondyl identity of Temnocorpichnus adds to the sparse and earliest records of temnspondyls, which are of Visean age. The smooth integument of the ichnogenus does not support the presence of ventral scales or armor in the earliest temnospondyls, but body proportions of the Mauch Chunk body impressions indicate a relatively terrestrial temnospondyl not matched by any taxon now known from bones. Three closely associated impressions of Temnocorpichnus on a single bedding plane suggest some sort of gregarious behavior in Mississippian temnospondyls and may support speculation that internal fertilization and associated courtship behavior evolved independently in one group of amphibians more than 300 million years ago.     

Unusual deinonychosaurian track morphology (Velociraptorichnus zhangi n. ichnosp.) from the Lower Cretaceous Xiaoba Formation,Sichuan Province,China

A new Lower Cretaceous dinosaur footprint locality named the Mujiaowu tracksite in the Xiaoba Formation, Sichuan Province, has yielded a new assemblage containing the didactyl deinonychosaurian ichnogenus Velociraptorichnus. This is the eleventh report in the global record, the seventh from Asia and the fifth from China. All, except for an isolated report from Europe, occur in Lower Cretaceous deposits. Unlike previous reports of the ichnogenus, the Mujiaowu site has yielded both didactyl Velociraptorichnus tracks and tridactyl tracks which we interpret as a different expression of this same ichnogenus, caused by registration of digit II, either due to special substrate conditions or to less claw retraction. These tridactyl Velociraptorichnus footprints are assigned to the new ichnospecies Velociraptorichnus zhangi. Such tridactyl deinonychosaurid footprint morphology is predictable, but based on current ichnological evidence appears to be the exception rather than the rule.     

Lacertoid Footprints of the Upper Permian Arenaria di Val Gardena Formation (Northern Italy)

Lacertoid footprints are the largest component of the Upper Permian Arenaria di Val Gardena Formation ichnofauna that contains hundreds of specimens mostly referred to the ichnogenus Rhynchosauroides Maidwell 1911. In this paper, we analyzed unpublished material and re-examined the Rhynchosauroides footprints of that ichnofauna, in particular the figured specimens. Analysis of Rhynchosauroides and its type ichnospecies R. rectipes Maidwell 1911 was first necessary. This preliminary investigation highlighted several problems, including ichnospecies named on the basis of poorly preserved material and in some cases significantly different from the type ichnospecies.

The study allowed for recognition of three ichnotaxa referred to Rhynchosauroides: Rhynchosauroides pallinii Conti et al., 1977, Rhynchosauroides isp.1 and Rhynchosauroides isp.2 and Ganasauripus ladinus igen. et isp. nov. Other material previously referred to Rhynchosauroides is herein regarded as unclassifiable, in the light of present ichnological knowledge and procedures.     

Ichnotaxonomic Review of Large Ornithopod Dinosaur Tracks: Temporal and Geographic Implications

BackgroundLarge ornithopod tracks are known from the Upper Jurassic to the uppermost Cretaceous rocks of all continents but Antarctica. They include the tracks historically called Iguanodon footprints, iguanodontid footprints, hadrosaur/hadrosaurid footprints, and other large ornithopod tracks that have been used to define ichnotaxa. More than 40 ichnospecies based on large ornithopod tracks have been defined, but the validity of many of them is questionable.Conclusions/SignificanceThe monospecific ichnogenus Iguanodontipus (I. burreyi) is characterized by a small, rounded heel and elongate, narrow digit impressions. Its distribution is limited to the Berriasian-Valanginian of Europe. Caririchnium consists of four ichnospecies (C. magnificum [type ichnospecies], C. kortmeyeri, C. billsarjeanti and C. lotus) with a large, rounded heel and short, wide digit impressions. This ichnogenus ranges from the Berriasian-Hauterivian to the Aptian-Albian of South America, North America, Asia and Europe. Finally, Hadrosauropodus (three ichnospecies: H. langstoni [type ichnospecies], H. leonardii and H. kyoungsookimi) shows a large, bilobed heel and short, wide digit impressions. It is known from the Aptian-Albian to the Maastrichtian of North America, Asia and Europe. The ichnofamily Iguanodontipodidae includes large iguanodontian tracks characterized mainly by mesaxonic, tridactyl and subsymmetrical pes tracks that are as wide as (or wider than) long and have one pad impression in each digit and one in the heel. Its distribution is confidently limited to the Cretaceous of Europe, Asia, North America and South America.     

Giant Eocene bird footprints from Northwest Washington,USA

Abstract. Tridactyl bird footprints preserved in Lower Eocene sandstone of the Chuckanut Formation in Whatcom County, Washington, USA, were made by a species of giant ground bird that walked along the subtropical lowland riverbank. The morphology and age of the tracks suggest the track maker was Diatryma (? = Gastornis). Although these birds have long been considered to be predators or scavengers, the absence of raptor‐like claws supports earlier suggestions that they were herbivores. The Chuckanut tracks are herein named as Rivavipes giganteus ichnogenus and ichnospecies nov., inferred to belong to the extinct family Gastornithidae.     

Behaviour of Dinosaurian Track-Makers in the Winton Formation (Cretaceous,Albian–Cenomanian) at Lark Quarry,Western Queensland,Australia: Running or Swimming?

A remarkable assemblage of dinosaur trackways in the Winton Formation (Albian–Cenomanian) at Lark Quarry, in western Queensland, Australia, has long been regarded as evidence of a stampede involving small theropods, whose tracks were classified in the ichnogenus Skartopus, and small ornithopods, whose tracks represented a second ichnogenus, Wintonopus. However, one recently-published study has claimed that existing interpretation of Lark Quarry is incorrect: it maintains that all the track-makers were ornithopods, that the ichnogenus Skartopus is a variant form of Wintonopus, and that most of the Lark Quarry track-makers were not running but more probably swimming downstream in a current of water. Those iconoclastic claims are investigated here and shown to be untenable. They derive from overgeneralized interpretation of the Lark Quarry track assemblage and invoke ad hoc auxiliary hypotheses which are either untestable or demonstrably incorrect. Closer inspection of the evidence underpinning those claims corroborates the existing interpretation of Lark Quarry as the site of a dinosaurian stampede and confirms the validity of the original distinction between theropod tracks (Skartopus) and ornithopod tracks (Wintonopus).     

Lower Cretaceous theropod tracks with the new ichnogenus and combination Lockleypus luanpingensis from the Dabeigou Formation of the Luanping Basin,Hebei Province,China

Theropod footprints from the Jingshang tracksite in the Lower Cretaceous Dabeigou Formation of the Luanping Basin, Hebei Province, China, are re-evaluated after new discoveries at this locality. They occur in a succession with sandstone, mudstone, and calcareous shale. The depositional environment was a shallow lake shore, comparable in age to the famous Jehol Biota. Based on the distinct morphology with peculiar features of the ratio of the outer digits, the footprints formerly assigned to Changpeipus carbonicus are now referred to the new ichnogenus and combination Lockleypus luanpingensis. The possible trackmaker was a relatively large ornithomimosaurian theropod thus far not known from the skeletal record of the Jehol Biota.