Pterosaur Assemblage Research Articles

A New Pterosaur Tracksite from the Jurassic Summerville Formation, Near Ferron, Utah

Pterosaur tracks (cf. Pteraichnus) from the Summerville Formation of the Ferron area of central Utah add to the growing record of Pteraichnus tracksites in the Late Jurassic Summerville Formation and time-equivalent, or near time-equivalent, deposits. The site is typical in revealing high pterosaur track densities, but low ichnodiversity suggesting congregations or “flocks” of many individuals. Footprint length varies from 2.0 to 7.0 cms. The ratio of well-preserved pes:manus tracks is about 1:3.4. This reflects a bias in favor of preservation of manus tracks due to the greater weight-bearing role of the front limbs, as noted in other pterosaur track assemblages. The sample also reveals a number of well-preserved trackways including one suggestive of pes-only progression that might be associated with take off or landing, and another that shows pronounced lengthening of stride indicating acceleration. One well-preserved medium-sized theropod trackway (Therangospodus) and other larger theropod track casts (cf. Megalosauripus) are associated with what otherwise appears to be a nearly monospecific pterosaur track assemblage. However, traces of a fifth pes digit suggest some tracks are of rhamphorynchoid rather than pterodactyloid origin, as usually inferred for Pteraichnus. The tracks occur at several horizons in a thin stratigraphic interval of ripple marked sandstones and siltstones. Overall the assemblage is similar to others found in the same time interval in the Western Interior from central and eastern Utah through central and southern Wyoming, Colorado, northeastern Arizona, and western Oklahoma. This vast “Pteraichnus ichnofacies,” with associated saurischian tracks, remains the only ichnological evidence of pre-Cretaceous pterosaurs in North America and sheds important light on the vertebrate ecology of the Summerville Formation and contiguous deposits.

An overview of the pterosaur assemblage from the Cambridge Greensand (Cretaceous) of Eastern England

An overview of the pterosaur assemblage from the Cambridge Greensand (Cretaceous) of Eastern England

An overview of the pterosaur assemblage from the Cambridge Greensand (Cretaceous) of Eastern England

The Cambridge Greensand, a remanié deposit that crops out in Cambridgeshire, eastern England, has yielded numerous, though fragmentary, late Early Cretaceous (Albian) vertebrate fossils including more than 2000 isolated pterosaur bones. So far, 32 species of pterosaur have been proposed in connection with the Cambridge Greensand material, but there has been and continues to be considerable confusion concerning the validity of these taxa, their relationships to each other and to other pterosaurs, and the material upon which they were established. A comprehensive systematic revision identified eleven valid species distributed among three families: the Ornithocheiridae (<i>Ornithocheirus simus</i> and possibly a second, as yet unnamed species of <i>Ornithocheirus, Coloborhynchus capito, Coloborhynchus sedgwickii, Anhanguera cuvieri</i>, and <i>Anhanguera fittoni</i>); the Lonchodectidae (<i>Lonchodectes compressirostris, Lonchodectes machaerorhynchus, Lonchodectes microdon</i> and <i>Lonchodectes platystomus</i>); and a species of edentulous pterosaur (<i>Ornithostoma sedgwicki</i>) that may represent the earliest record for the Pteranodontidae. It is possible that some of the taxa currently recognised represent sexual dimorphs (<i>Coloborhynchus capito</i> and <i>Coloborhynchus sedgwickii, Lonchodectes compressirostris</i> and <i>Lonchodectes machaerorhynchus</i>), or disjunct populations of a single species (<i>Ornithocheirus simus</i> and <i>Ornithocheirus</i> sp., <i>Lonchodectes compressirostris</i> and <i>Lonchodectes microdon</i>) and that there may be as few as seven valid species, but the Cambridge Greensand pterosaurs are too poorly known to demonstrate this at present. The Cambridge Greensand pterosaur assemblage is similar to a slightly younger, but much smaller assemblage from the Lower Chalk of England and shares some elements, such as ornithocheirids, in common with many other late Early and early Late Cretaceous assemblages. It is distinguished by the absence of tapejarids and the presence of <i>Lonchodectes</i> which, so far, is only known from the Cretaceous of England. The disparity in taxonomic composition is possibly related to ecological differentiation, and might also reflect some provincialism in late Early and early Late Cretaceous pterosaur faunas. <br><br> Der Cambridge Greensand, eine in Ostengland aufgeschlossene Remanié-Ablagerung, hat zahlreiche Wirbeltiere aus der oberen Unterkreide (Alb) geliefert. Darunter fanden sich mehr als 2000 isolierte Pterosaurierknochen. Insgesamt wurden aus dem Greensand bis zu 32 Flugsauriertaxa beschrieben, was zu einer beträchtlichen taxonomischen und nomenklatorischen Verwirrung geführt hat, die bis heute andauert. Eine vollständige Revision erkennt 11 Arten aus drei Familien an: (1) die Ornithocheiridae (<i>Ornithocheirus simus</i> und vielleicht eine zweite, bislang unbenannte Art von <i>Ornithocheirus</i>, sowie <i>Coloborhynchus capito, Coloborhynchus sedgwickii, Anhanguera cuvieri</i> und <i>Anhanguera fittoni</i>); (2) die Lonchodectidae (<i>Lonchodectes compressirostris, Lonchodectes machaerorhynchus, Lonchodectes microdon</i> und <i>Lonchodectes platystomus</i>); und schließlich einen zahnlosen Flugsaurier (<i>Ornithostoma sedgwicki</i>). der zu keiner der vorgenannten Familien gehört und sich als stratigraphisch ältester Nachweis der Pteranodontidae erweisen könnte. Es ist nicht auszuschließen, dass einige der gegenwärtig erkannten Taxa eher einen ausgeprägten Sexualdimorphismus illustrieren denn taxonomisch distinkte Arten darstellen (<i>Coloborhynchus capito</i> und <i>Coloborhynchus sedgwickii</i>, <i>Lonchodectes compressirostris</i> und <i>Lonchodectes machaerorhynchus</i>) oder sogar lediglich Endpunkte einer intraspezifisch variablen Population (<i>Ornithocheirus simus</i> und <i>Ornithocheirus</i> sp., <i>Lonchodectes compressirostris</i> und <i>Lonchodectes microdon</i>). In dieser strengeren Fassung bestünden nur sieben gültige Arten, doch leider sind die Flugsaurier des Cambridge Greensand zu schlecht bekannt, um diese Fragen zu beantworten. Die Flugsaurierfauna des Cambridge Greensand ähnelt jüngeren kreidezeitlichen Faunen aus dem Lower Chalk von England. Weiter-hin enthält sie Faunenelemente, wie etwa Ornithocheiriden. die auch für zahlreiche andere Faunen der hohen Unterkreide und tiefen Oberkreide charakteristisch sind. Das Fehlen von Tapejariden und das Auftreten des anscheinend endemischen <i>Lonchodectes</i> sind weitere Kennzeichen des Cambridge Greensand. Die Zusammensetzung der Pterosaurierfaunen folgte offenbar ökologischen Differenzierungen und illustriert einen gewissen Provinzialismus an der Grenze Unter-Oberkreide. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.20010040112" target="_blank">10.1002/mmng.20010040112</a>

Pterosaur remains from the Cretaceous of Morocco

New pterosaur remains consisting of jaw fragments of toothless taxa and isolated teeth are described from the red beds of the Kern Kern region of southern Morocco. The stratigraphic position of those red beds is discussed and it is concluded that they are in all likelihood early Cenomanian in age. At least four taxa of pterodactyloid pterosaurs are present. The toothless jaw fragments are referred to the families ?Pteranodontidae, ?Azhdarchidae and Tapejaridae. Four different morphotypes can be distinguished among the isolated teeth. They are tentatively referred to the Ornithocheiridae. This assemblage reveals a high diversity of pterosaurs in Africa during the early Upper Cretaceous. The possible occurrence of tapejarids and anhanguerids indicates relationships with the somewhat older pterosaur assemblage from the Santana Formation (Aptian/Albian) of Brazil. If confirmed, the presence of azhdarchids and pteranodontids in the early Cenomanian suggests an early differentiation of these essentially late Late Cretaceous groups of large pterosaurs.