Publications in the Year: 2015

Conference Paper

Marzola, M, Mateus O, Schulp AS, Jacobs LL, Polcyn MJ, Pervov V, Goncalves AO, Morais ML.  2015.  Comparative anatomy and systematics of Cretaceous mammal tracks of Angola, July 2015. 13th Annual Meeting of the European Association of Vertebrate Palaeontologists - EAVP 2015. , Opole, Poland: European Association of Vertebrate Palaeontologistsmarzola_et_al_2015_catoca_tracks_eavp.pdf

Conference Proceedings

Polcyn, MJ, Jacobs LL, Schulp AS, Mateus O.  2015.  Trolling the Cretaceous Seas: Marine Amniotes of Two West Coast Margins. Geological Society of America Annual Meeting. :55.: Geological Society of America Abstracts with Programs. Vol. 47, No. 4, p.55 Abstract

In this session we review the Upper Cretaceous marine amniote records from the west coasts of North America and Africa. Recent work by our group in Angola, on the west coast of Africa, has opened up new fossiliferous localities, producing well-preserved turtles, plesiosaurs, and mosasaurs, ranging in age from Late Turonian to Late Maastrichtian. These African localities were deposited in arid latitudes and highly productive upwelling zones along the passive margin of a growing South Atlantic Ocean. The fossil record of Cretaceous marine amniotes from the West Coast of North America is relatively meager when compared to the African record and the prolific fossil beds laid down in the epicontinental seas of the Western Interior Seaway and northern Europe. Nonetheless, these localities provide an important glimpse of a marine ecosystem that developed on the active margins of a deep ocean basin. Historically considered to be depauperate and endemic, the west coast fauna was characterized by unusual forms such as Plotosaurus, arguably one of the most derived mosasaurs; however, in recent years, additional taxa have been described, revealing species diversity and ecological partitioning within these communities and in some cases, faunal interchange with other regions. The large quantity of well-preserved fossils from the west coast of Africa is influenced in part by its paleogeographic position, deposited within highly productive areas of Hadley Cell controlled upwelling zones. By contrast, the North American west coast localities have been deposited in temperate and higher latitudes since the Late Cretaceous. Nonetheless, the North American and African faunas share some common characteristics in a possessing a mix of endemic and more cosmopolitan forms. Habitat partitioning reflected in tooth form and body size is comparable between the Angolan and the North American west coast, and there is remarkable convergence in taxa which appear to exploit certain like-niches.

Polcyn, MJ, Jacobs LL, Schulp AS, Mateus O, Araújo R.  2015.  Tethyan and Weddellian biogeographic mixing in the Maastrichtian of Angola. Annual Meeting of the Society of Vertebrate Paleontology. :196., Dallas, TXpolcyn_etal2015_mix_fauna_angola_svp_abstract.pdf
Mateus, O, Jacobs LL, Polcyn MJ, Myers TS, Schulp AS.  2015.  The fossil record of testudines from angola from the turonian to oligocene. Society of Vertebrate Paleontology Annual Meeting. :177., Dallasmateus_et_al_2015_testudines_angola_svp_abstract.pdf

Journal Article

Strganac, C, Jacobs LL, Polcyn MJ, Ferguson KM, Mateus O, Gonçalves OA, Morais M-L, da Silva Tavares T.  2015.  Stable oxygen isotope chemostratigraphy and paleotemperature regime of mosasaurs at Bentiaba, Angola, 2. Netherlands Journal of Geosciences. FirstView:1–7. Abstractstrganac_etal2015_stable_oxigen_isotopes.pdfWebsite

ABSTRACT Stable oxygen isotope values of inoceramid marine bivalve shells recovered from Bentiaba, Angola, are utilised as a proxy for paleotemperatures during the Late Cretaceous development of the African margin of the South Atlantic Ocean. The δ18O values derived from inoceramids show a long-term increase from –3.2‰ in the Late Turonian to values between –0.8 and –1.8‰ in the Late Campanian. Assuming a constant oceanic δ18O value, an ∼2‰ increase may reflect cooling of the shallow marine environment at Bentiaba by approximately 10°. Bentiaba values are offset by about +1‰ from published records for bathyal Inoceramus at Walvis Ridge. This offset in δ18O values suggests a temperature difference of ∼5° between coastal and deeper water offshore Angola. Cooler temperatures implied by the δ18O curve at Bentiaba coincide with the stratigraphic distribution of diverse marine amniotes, including mosasaurs, at Bentiaba.

Young, MT, Hua S, Steel L, Foffa D, Brusatte SL, Thüring S, Mateus O, Ruiz-Omeñaca JI, Havlik P, Lepage Y, de Andrade MB.  2015.  Addendum to ‘Revision of the Late Jurassic teleosaurid genus Machimosaurus (Crocodylomorpha, Thalattosuchia)’. Royal Society Open Science. 2, Number 2: The Royal Society Abstractyoung_et_al_2015_addendum_to_revision_of_the_late_jurassic_teleosaurid_genus_machimosaurus_crocodylomorpha_thalattosuchia.pdfWebsite

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Strganac, C, Jacobs L, Polcyn M, Mateus O, Myers T, Araújo R, Fergunson KM, Gonçalves AO, Morais ML, Schulp AS, da Tavares TS, Salminen J.  2015.  Geological Setting and Paleoecology of the Upper Cretaceous Bench 19 Marine Vertebrate Bonebed at Bentiaba, Angola. Netherlands Journal of Geosciences. 94(1):121-136. Abstractstrganac_et_al_2014_geological_setting_bentiaba_angola.pdfWebsite

The Bench 19 Bonebed at Bentiaba, Angola, is a unique concentration of marine vertebrates preserving six species of mosasaurs in sediments best correlated by magnetostratigraphy to chron C32n.1n between 71.4 and 71.64 Ma. The bonebed formed at a paleolatitude near 24°S, with an Atlantic width at that latitude approximating 2700 km, roughly half that of the current width. The locality lies on an uncharacteristically narrow continental shelf near transform faults that controlled the coastal outline of Africa in the formation of the South Atlantic Ocean. Biostratigraphic change through the Bentiaba section indicates that the accumulation occurred in an ecological time dimension within the 240 ky bin delimited by chron 32n.1n. The fauna occurs in a 10 m sand unit in the Mocuio Formation with bones and partial skeletons concentrated in, but not limited to, the basal 1–2 m. The sediment entombing the fossils is an immature feldspathic sand shown by detrital zircon ages to be derived from nearby granitic shield rocks. Specimens do not appear to have a strong preferred orientation and they are not concentrated in a strand line. Stable oxygen isotope analysis of associated bivalve shells indicates a water temperature of 18.5°C. The bonebed is clearly mixed with scattered dinosaur and pterosaur elements in a marine assemblage. Gut contents, scavenging marks and associated shed shark teeth in the Bench 19 Fauna indicate biological association and attrition due to feeding activities. The ecological diversity of mosasaur species is shown by tooth and body-size disparity and by δ13C analysis of tooth enamel, which indicate a variety of foraging areas and dietary niches. The Bench 19 Fauna was formed in arid latitudes along a coastal desert similar to that of modern Namibia on a narrow, tectonically controlled continental shelf, in shallow waters below wave base. The area was used as a foraging ground for diverse species, including molluscivorus Globidens phosphaticus, small species expected near the coast, abundant Prognathodon kianda, which fed on other mosasaurs at Bench 19, and species that may have been transient and opportunistic feeders in the area.

Araújo, R, Polcyn MJ, Lindgren J, Jacobs LL, Schulp AS, Mateus O, Gonçalves OA, Morais M-L.  2015.  New aristonectine elasmosaurid plesiosaur specimens from the Early Maastrichtian of Angola and comments on paedomorphism in plesiosaurs, 2. Netherlands Journal of Geosciences. FirstView:1–16. Abstractaraujo_et_al_2015_paedomorphism-libre.pdfWebsite

ABSTRACT New elasmosaurid plesiosaur specimens are described from the Early Maastrichtian of Angola. Phylogenetic analyses reconstruct the Angolan taxon as an aristonectine elasmosaurid and the sister taxon of an unnamed form of similar age from New Zealand. Comparisons also indicate a close relationship with an unnamed form previously described from Patagonia. All of these specimens exhibit an ostensibly osteologically immature external morphology, but histological analysis of the Angolan material suggests an adult with paedomorphic traits. By extension, the similarity of the Angolan, New Zealand and Patagonian material indicates that these specimens represent a widespread paedomorphic yet unnamed taxon.

Hendrickx, C, Mateus O, Araújo R.  2015.  A proposed terminology of theropod teeth (Dinosauria, Saurischia). Journal of Vertebrate Paleontology. :e982797. Abstracthendrickx_et_al_2015_theropod_teeth_svp.pdfWebsite

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Clemmensen, LB, Milàn J, Adolfssen JS, Estrup EJ, Frobøse N, Klein N, Mateus O, Wings O.  2015.  The vertebrate-bearing Late Triassic Fleming Fjord Formation of central East Greenland revisited: stratigraphy, palaeoclimate and new palaeontological data. Geological Society, London, Special Publications. 434(1):31-47. Abstractclemmensenetal2015greenland.pdfWebsite

In Late Triassic (Norian–Rhaetian) times, the Jameson Land Basin lay at 40° N on the northern part of the supercontinent Pangaea. This position placed the basin in a transition zone between the relatively dry interior of the supercontinent and its more humid periphery. Sedimentation in the Jameson Land Basin took place in a lake–mudflat system and was controlled by orbitally forced variations in precipitation. Vertebrate fossils have consistently been found in these lake deposits (Fleming Fjord Formation), and include fishes, dinosaurs, amphibians, turtles, aetosaurs and pterosaurs. Furthermore, the fauna includes mammaliaform teeth and skeletal material. New vertebrate fossils were found during a joint vertebrate palaeontological and sedimentological expedition to Jameson Land in 2012. These new finds include phytosaurs, a second stem testudinatan specimen and new material of sauropodomorph dinosaurs, including osteologically immature individuals. Phytosaurs are a group of predators common in the Late Triassic, but previously unreported from Greenland. The finding includes well-preserved partial skeletons that show the occurrence of four individuals of three size classes. The new finds support a late Norian–early Rhaetian age for the Fleming Fjord Formation, and add new information on the palaeogeographical and palaeolatitudinal distribution of Late Triassic faunal provinces.

Pereira, BC, Benton MJ, Ruta M, Mateus O.  2015.  Mesozoic echinoid diversity in Portugal: Investigating fossil record quality and environmental constraints on a regional scale. Palaeogeography, Palaeoclimatology, Palaeoecology. 424:132-146. Abstractpereira_e_al_2015_mesozoic_echinoids_portugal.pdfWebsite

Abstract Several analyses of diversity through geological time use global, synoptic databases, and this practice often makes it difficult to distinguish true signals in changing diversity from regional-scale sampling and/or geological artefacts. Here we investigate how echinoid diversity changed through the Mesozoic of the Lusitanian basin in Portugal based on a comprehensive, revised database, and seek to distinguish biological signal from geological or environmental constraints. The observed diversity pattern is far from having a defined trend, showing many fluctuations that appear to be linked with gaps in the geological record. This study revealed that, independently of the method used, whether correlation tests or model fitting, the diversity signal is not completely explained by the studied sampling proxies. Among the different proxies, marine facies variation in combination with outcrop area best explains the palaeodiversity curve.

Hendrickx, C, Mateus O, Araújo R.  2015.  The dentition of megalosaurid theropods. Acta Palaeontologica Polonica. 60(3):627–642. Abstracthendrickx_et_al_2015_theropod_teeth_app.pdfWebsite

Theropod teeth are particularly abundant in the fossil record and frequently reported in the literature. Yet, the dentition of many theropods has not been described comprehensively, omitting details on the denticle shape, crown ornamentation and enamel texture. This paucity of information has been particularly striking in basal clades, thus making identification of isolated teeth difficult, and taxonomic assignments uncertain. We here provide a detailed description of the dentition of Megalosauridae, and a comparison to and distinction from superficially similar teeth of all major theropod clades. Megalosaurid dinosaurs are characterized by a mesial carina facing mesiolabially in most mesial teeth, centrally positioned carinae on both most mesial and lateral crowns, a mesial carina terminating above the cervix, and short to well-developed interdenticular sulci between distal denticles. A discriminant analysis performed on a dataset of numerical data collected on the teeth of 62 theropod taxa reveals that megalosaurid teeth are hardly distinguishable from other theropod clades with ziphodont dentition. This study highlights the importance of detailing anatomical descriptions and providing additional morphometric data on teeth with the purpose of helping to identify isolated theropod teeth in the future.

Foth, C, Evers S, Pabst B, Mateus O, Flisch A, Patthey M, Rauhut OWM.  2015.  New insights into the lifestyle of Allosaurus (Dinosauria: Theropoda) based on another specimen with multiple pathologies, 2015. PeerJ PrePrints. 3:e824v1. Abstractfoth_et_al_2015_peerj-preprints-824.pdfWebsite

Adult large-bodied theropods are often found with numerous pathologies. A large, almost complete, probably adult Allosaurus specimen from the Howe Stephens Quarry, Morrison Formation (Late Kimmeridgian–Early Tithonian), Wyoming, shows multiple pathologies. Pathologic bones include the left dentary, two cervical vertebrae, one cervical and several dorsal ribs, the left scapula, the left humerus, right ischium, and two left pedal phalanges. These pathologies can be classified as follows: the fifth cervical vertebra, the scapula, several ribs and the ischium are traumatic, and a callus on the shaft of the left pedal phalanx II-2 is traumatic-infectious. Traumatically fractured elements exposed to frequent movement (e.g. the scapula and the ribs) show a tendency to develop pseudarthroses instead of callus healing. The pathologies in the lower jaw and a reduced flexor tubercle of the left pedal phalanx II-2 are most likely traumatic or developmental in origin. The pathologies on the fourth cervical are most likely developmental in origin or idiopathic, that on the left humerus is infectious or idiopathic, whereas left pedal phalanx IV-1 is classified as idiopathic. With exception of the ischium, all traumatic / traumatic-infectious pathologic elements show unambiguous evidences of healing, indicating that the respective pathologies did not cause the death of this individual. Alignment of the scapula and rib pathologies from the left side suggests that all may have been caused by a single traumatic event. The ischial fracture may have been fatal. The occurrence of multiple traumatic pathologies again underlines that large-bodied theropods experienced frequent injuries during life, indicating an active predatory lifestyle, and their survival perhaps supports a gregarious behavior for Allosaurus. Signs of infections are scarce and locally restricted, indicating a successful prevention of the spread of pathogens, as it is the case in extant reptiles (including birds).

Tschopp, E, Mateus O, Benson RBJ.  2015.  A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda), 4. PeerJ. 3:e857. Abstracttschopp_et_al_2015_brontosaurus_peerj-857.pdfWebsite

Diplodocidae are among the best known sauropod dinosaurs. Several species were described in the late 1800s or early 1900s from the Morrison Formation of North America. Since then, numerous additional specimens were recovered in the USA, Tanzania, Portugal, and Argentina, as well as possibly Spain, England, Georgia, Zimbabwe, and Asia. To date, the clade includes about 12 to 15 nominal species, some of them with questionable taxonomic status (e.g., ‘\textit{Diplodocus}’ \textit{hayi} or \textit{Dyslocosaurus polyonychius}), and ranging in age from Late Jurassic to Early Cretaceous. However, intrageneric relationships of the iconic, multi-species genera \textit{Apatosaurus} and \textit{Diplodocus} are still poorly known. The way to resolve this issue is a specimen-based phylogenetic analysis, which has been previously implemented for \textit{Apatosaurus}, but is here performed for the first time for the entire clade of Diplodocidae.The analysis includes 81 operational taxonomic units, 49 of which belong to Diplodocidae. The set of OTUs includes all name-bearing type specimens previously proposed to belong to Diplodocidae, alongside a set of relatively complete referred specimens, which increase the amount of anatomically overlapping material. Non-diplodocid outgroups were selected to test the affinities of potential diplodocid specimens that have subsequently been suggested to belong outside the clade. The specimens were scored for 477 morphological characters, representing one of the most extensive phylogenetic analyses of sauropod dinosaurs. Character states were figured and tables given in the case of numerical characters.The resulting cladogram recovers the classical arrangement of diplodocid relationships. Two numerical approaches were used to increase reproducibility in our taxonomic delimitation of species and genera. This resulted in the proposal that some species previously included in well-known genera like \textit{Apatosaurus} and \textit{Diplodocus} are generically distinct. Of particular note is that the famous genus \textit{Brontosaurus} is considered valid by our quantitative approach. Furthermore, “\textit{Diplodocus}” hayi represents a unique genus, which will herein be called \textit{Galeamopus} gen. nov. On the other hand, these numerical approaches imply synonymization of “\textit{Dinheirosaurus}” from the Late Jurassic of Portugal with the Morrison Formation genus \textit{Supersaurus}. Our use of a specimen-, rather than species-based approach increases knowledge of intraspecific and intrageneric variation in diplodocids, and the study demonstrates how specimen-based phylogenetic analysis is a valuable tool in sauropod taxonomy, and potentially in paleontology and taxonomy as a whole.

Marzola, M, Russo J, Mateus O.  2015.  Identification and comparison of modern and fossil crocodilian eggs and eggshell structures. Historical Biology. 27(1):115-133. Abstractmarzola_et_al_2015_identification_and_comparison_of_modern_and_fossil_crocodilian_eggs_and_eggshell_structures.pdfWebsite

Eggshells from the three extant crocodilian species Crocodylus mindorensis (Philippine Crocodile), Paleosuchus palpebrosus (Cuvier's Smooth-fronted Caiman or Musky Caiman) and Alligator mississippiensis (American Alligator or Common Alligator) were prepared for thin section and scanning electron microscope analyses and are described in order to improve the knowledge on crocodilian eggs anatomy and microstructure, and to find new apomorphies that can be used for identification. Both extant and fossil crocodilian eggs present an ornamentation that vary as anastomo-, ramo- or the here newly described rugosocavate type. The angusticaniculate pore system is a shared character for Crocodylomorpha eggshells and some dinosaurian and avian groups. Previously reported signs of incubated crocodilian eggs were found also on our only fertilised and hatched egg. Paleosuchus palpebrosus presents unique organization and morphology of the three eggshell layers, with a relatively thin middle layer characterised by dense and compact tabular microstructure.

Araújo, R, Polcyn MJ, Schulp AS, Mateus O, Jacobs LL, Gonçalves OA, Morais M-L.  2015.  A new elasmosaurid from the early Maastrichtian of Angola and the implications of girdle morphology on swimming style in plesiosaurs, 1. Netherlands Journal of Geosciences. FirstView:1–12. Abstractaraujo_et_al_2015_a_new_elasmosaurid_from_the_early_maastrichtian_of_angola.pdfWebsite

ABSTRACT We report here a new elasmosaurid from the early Maastrichtian at Bentiaba, southern Angola. Phylogenetic analysis places the new taxon as the sister taxon to Styxosaurus snowii, and that clade as the sister of a clade composed of (Hydrotherosaurus alexandrae (Libonectes morgani + Elasmosaurus platyurus)). The new taxon has a reduced dorsal blade of the scapula, a feature unique amongst elasmosaurids, but convergent with cryptoclidid plesiosaurs, and indicates a longitudinal protraction-retraction limb cycle rowing style with simple pitch rotation at the glenohumeral articulation. Morphometric phylogenetic analysis of the coracoids of 40 eosauropterygian taxa suggests that there was a broad range of swimming styles within the clade.

Brusatte, SL, Butler RJ, Mateus O, Steyer SJ.  2015.  A new species of Metoposaurus from the Late Triassic of Portugal and comments on the systematics and biogeography of metoposaurid temnospondyls, 2015. Journal of Vertebrate PaleontologyJournal of Vertebrate Paleontology. :e912988.: Taylor & Francis Abstractbrusatte_et_al2015metoposaurusportugal.pdfWebsite

ABSTRACTMetoposaurids are a group of temnospondyl amphibians that filled crocodile-like predatory niches in fluvial and lacustrine environments during the Late Triassic. Metoposaurids are common in the Upper Triassic sediments of North Africa, Europe, India, and North America, but many questions about their systematics and phylogeny remain unresolved. We here erect Metoposaurus algarvensis, sp. nov., the first Metoposaurus species from the Iberian Peninsula, based on several new specimens from a Late Triassic bonebed in Algarve, southern Portugal. We describe the cranial and pectoral anatomy of M. algarvensis and compare it with other metoposaurids (particularly other specimens of Metoposaurus from Germany and Poland). We provide a revised diagnosis and species-level taxonomy for the genus Metoposaurus, which is currently represented with certainty by three European species (M. diagnosticus, M. krasiejowensis, M. algarvensis). We also identify cranial characters that differentiate these three species, and may have phylogenetic significance. These include features of the braincase and mandible, which indicate that metoposaurid skulls are more variable than previously thought. The new Portuguese bonebed provides further evidence that metoposaurids congregated in fluvial and lacustrine settings across their geographic range and often succumbed to mass death events. We provide an updated paleogeographic map depicting all known metoposaurid occurrences, which shows that these temnospondyls were globally distributed in low latitudes during the Late Triassic and had a similar, but not identical, paleogeographic range as phytosaurs.http://zoobank.org/urn:lsid:zoobank.org:pub:083C80C6-0AB6-49E1-A636-6A8BDBC06A47ABSTRACTMetoposaurids are a group of temnospondyl amphibians that filled crocodile-like predatory niches in fluvial and lacustrine environments during the Late Triassic. Metoposaurids are common in the Upper Triassic sediments of North Africa, Europe, India, and North America, but many questions about their systematics and phylogeny remain unresolved. We here erect Metoposaurus algarvensis, sp. nov., the first Metoposaurus species from the Iberian Peninsula, based on several new specimens from a Late Triassic bonebed in Algarve, southern Portugal. We describe the cranial and pectoral anatomy of M. algarvensis and compare it with other metoposaurids (particularly other specimens of Metoposaurus from Germany and Poland). We provide a revised diagnosis and species-level taxonomy for the genus Metoposaurus, which is currently represented with certainty by three European species (M. diagnosticus, M. krasiejowensis, M. algarvensis). We also identify cranial characters that differentiate these three species, and may have phylogenetic significance. These include features of the braincase and mandible, which indicate that metoposaurid skulls are more variable than previously thought. The new Portuguese bonebed provides further evidence that metoposaurids congregated in fluvial and lacustrine settings across their geographic range and often succumbed to mass death events. We provide an updated paleogeographic map depicting all known metoposaurid occurrences, which shows that these temnospondyls were globally distributed in low latitudes during the Late Triassic and had a similar, but not identical, paleogeographic range as phytosaurs.http://zoobank.org/urn:lsid:zoobank.org:pub:083C80C6-0AB6-49E1-A636-6A8BDBC06A47

Hendrickx, C, Hartman SA, Mateus O.  2015.  An overview of non-avian theropod discoveries and classification. PalArch’s Journal of Vertebrate Palaeontology. 12(1):1-73. Abstracthendrickx_etal_2015_non_avian_theropods_pjvp12_11.pdfWebsite

Theropods form a taxonomically and morphologically diverse group of dinosaurs that include extant birds. Inferred relationships between theropod clades are complex and have changed dramatically over the past thirty years with the emergence of cladistic techniques. Here, we present a brief historical perspective of theropod discoveries and classification, as well as an overview on the current systematics of non-avian theropods. The first scientifically recorded theropod remains dating back to the 17th and 18th centuries come from the Middle Jurassic of Oxfordshire and most likely belong to the megalosaurid Megalosaurus. The latter was the first theropod genus to be named in 1824, and subsequent theropod material found before 1850 can all be referred to megalosauroids. In the fifty years from 1856 to 1906, theropod remains were reported from all continents but Antarctica. The clade Theropoda was erected by Othniel Charles Marsh in 1881, and in its current usage corresponds to an intricate ladder-like organization of ‘family’ to ‘superfamily’ level clades. The earliest definitive theropods come from the Carnian of Argentina, and coelophysoids form the first significant theropod radiation from the Late Triassic to their extinction in the Early Jurassic. Most subsequent theropod clades such as ceratosaurs, allosauroids, tyrannosauroids, ornithomimosaurs, therizinosaurs, oviraptorosaurs, dromaeosaurids, and troodontids persisted until the end of the Cretaceous, though the megalosauroid clade did not extend into the Maastrichtian. Current debates are focused on the monophyly of deinonychosaurs, the position of dilophosaurids within coelophysoids, and megaraptorans among neovenatorids. Some recent analyses have suggested a placement of dilophosaurids outside Coelophysoidea, Megaraptora within Tyrannosauroidea, and a paraphyletic Deinonychosauria with troodontids placed more closely to avialans than dromaeosaurids.

Xing, L, Lockley MG, Marty D, Zhang J, Wang Y, Klein H, McCrea RT, Buckley LG, Belvedere M, Mateus O, Gierliński GD, Piñuela L, Persons, IV SW, Wang F, Ran H, Dai H, Xie X.  2015.  An Ornithopod-Dominated Tracksite from the Lower Cretaceous Jiaguan Formation (Barremian–Albian) of Qijiang, South-Central China: New Discoveries, Ichnotaxonomy, Preservation and Palaeoecology, 10. PLoS ONE. 10:e0141059., Number 10: Public Library of Science Abstractlida_et_al_2015_an_ornithopod-dominated_tracksite_from_the.pdfWebsite

The historically-famous Lotus Fortress site, a deep 1.5–3.0-meter-high, 200-meter-long horizonal notch high up in near-vertical sandstone cliffs comprising the Cretaceous Jiaguan Formation, has been known since the 13th Century as an impregnable defensive position. The site is also extraordinary for having multiple tetrapod track-bearing levels, of which the lower two form the floor of part of the notch, and yield very well preserved asseamblages of ornithopod, bird (avian theropod) and pterosaur tracks. Trackway counts indicate that ornithopods dominate (69%) accounting for at least 165 trackmakers, followed by bird (18%), sauropod (10%), and pterosaur (3%). Previous studies designated Lotus Fortress as the type locality of Caririchnium lotus and Wupus agilis both of which are recognized here as valid ichnotaxa. On the basis of multiple parallel trackways both are interpreted as representing the trackways of gregarious species. C. lotus is redescribed here in detail and interpreted to indicate two age cohorts representing subadults that were sometimes bipedal and larger quadrupedal adults. Two other previously described dinosaurian ichnospecies, are here reinterpreted as underprints and considered nomina dubia. Like a growing number of significant tetrapod tracksites in China the Lotus Fortress site reveals new information about the composition of tetrapod faunas from formations in which the skeletal record is sparse. In particular, the site shows the relatively high abundance of Caririchium in a region where saurischian ichnofaunas are often dominant. It is also the only site known to have yielded Wupus agilis. In combination with information from other tracksites from the Jiaguan formation and other Cretaceous formations in the region, the track record is proving increasingly impotant as a major source of information on the vertebrate faunas of the region. The Lotus Fortress site has been developed as a spectacular, geologically-, paleontologically- and a culturally-significant destination within Qijiang National Geological Park.