Archive for category PalArch’s Journal of Vertebrate Palaeontology

Abstract Marine turtle fossils are extremely rare in the Muwaqqar Chalk Marl Formation of the Harrana Fauna in comparison to the relatively rich variety of other vertebrate fossils collected from this locality. This paper reports and describes the remains of an extinct marine turtle (Chelonioidea) which will be tentatively assigned to a new genus and species of marine turtles (Cheloniidae Bonaparte, 1835) Gigantatypus salahi n.gen., n.sp.. The new genus represented by a single well–preserved right humerus, reached remarkably large proportions equivalent to that of Archelon Wieland, 1896 and represents the first to be found from this deposit and from the Middle East. The specimen, which exhibits unique combinations of features is characterized by the following morphological features not found in other members of the Cheloniidae: massive species reaching over 12 feet in length; a more prominently enlarged lateral process that is situated more closely to the head; a ventrally situated capitellum; a highly laterally expanded distal margin. The presence of these features may warrant the placement of this new species in a new genus. The specimen also retains some morphological features found in members of advanced protostegids indicating close affinities with the family. Several bite marks on the ventral surface of the fossilized humerus indicate shark–scavenging activities of possibly Squalicorax spp.

Abstract Bajpai et al.’s recent paper (2005a) describing an important new Early Eocene mammal fauna from the Cambay Shale of Vastan Lignite Mine, Gujarat, India has a number of errors related to identification, naming, definition, characterisation and description of new taxa, and measurements of dentitions etc. that need to be recorded and addressed. This contribution discusses and clarifies some of the errors and will be useful for understanding the real impact of the Vastan fauna in relation to the India-Asia collision, the mammalian palaeobiogeography and origin of modern placental mammals.

Abstract Specimens initially collected but not reported from the original type locality of Cornwallius sookensis (Mammalia, Desmostylia) have been found at the National Museum of Natural History in Washington, DC. Two femora and a partial skull were collected from the same locality as the holotype that was deposited by Ira Cornwall in the Royal British Columbia Provincial Museum in the 1920s. Though the partial skull is missing from the collection, the femora remain. They are small and lack epiphyses, possibly from breakage or immaturity. Muscle scars suggest that adductors, extensors and lateral rotators were strongly developed, indicating that their posture was of the normal mammalian upright nature. The sectioned end of USNM 11076 permits inspection of characteristics of the medullary canal and cortical.

Abstract The pectoral girdle of Hydrotherosaurus alexandrae Welles 1943, an elasmosaurid plesiosaur from the Upper Cretaceous (Maastrichtian) of California, USA, is redescribed. Some differences to the reconstruction presented in the original description, as well as newly discovered features of the pectoral girdle are discussed and a new reconstruction is provided.

Abstract Predator–prey interactions shown by ichnofossils are not very frequent and the interpretation of so–called ‘terminated trackways’ can represent a good opportunity of study. Especially the behavioural tendency of some vertebrates can be confirmed. In the Lower Permian of the Valtellina area (Orobic Basin, Southalpine, North Italy) a very peculiar development of arthropod walking–trails (Dendroidichnites elegans Demathieu, Gand & Toutin–Morin, 1992 and cfr. Heteropodichnus variabilis Walter, 1983) and the presence in suspicious position of Dromopus sp. footprints, should testify a possible predation attempt from the vertebrate maker on the formers. Thus, during the Lower Permian it should be also documented that the partial predator role in the Southalpine, was occupied just by the araeoscelid trackmaker of the Dromopus. Inside the trophic pyramid, probably with the Varanopus and Camunipes ones, Dromopus’s maker occupied the opportunist consumer role. Amphisauropus latus Haubold, 1971 and A. imminutus Haubold, 1971 makers played the primary consumer role, while a true carnivore is missing.

Abstract When E.D. Cope described the type specimen of Elasmosaurus platyurus 1868 more completely in 1869, he noted that a number of dorsal vertebrae were missing, along with the gastralia, the limbs, and most of the skull. Although the military surgeon who discovered the remains, Dr. Theophilus H. Turner, made additional searches the missing material was never located. Interest in the specimen eventually faded as dinosaurs were discovered further west, and portions of the specimen, including the pectoral and pelvic girdles, were mysteriously lost. More recently, three collections of associated plesiosaur material, including dorsal vertebrae, ribs, gastralia, and large gastroliths were made from a second site near the type locality of E. platyurus. The additional material is curated in the Sternberg Museum of Natural History, Hays, KS, the University of Kansas Museum of Natural History, Lawrence, KS, and the Cincinnati Museum Center, Cincinnati, OH. Examination the more recently discovered remains in these three repositories, and comparisons with the those of the type specimen at the Academy of Natural Sciences of Philadelphia, a review of the letters and other historical documents related to the discovery of E. platyurus, and on–site evaluation of the stratigraphy of the both localities suggest that the more recently collected remains were originally part of the type specimen and were separated prior to burial when the floating carcass began to fall apart.

Abstract A jaw fragment of what was most likely a placodontoid marine reptile has been reported from the Lower Muschelkalk of Winterswijk. The fragment is too small for determination on the species level but the typical tooth replacement of the placodontoid family can just be recognised. The teeth however are far smaller than fitting to any of the known species if not belonging to a juvenile.

Abstract Ursus spelaeus from the Buco dell’Orso Cave (Lombardy, North Italy) has some peculiar metrical characteristics that make it more close to Ursus deningeri rather than to the typical spelaeus. In particular, it is the smaller size that makes the difference. In this study, the ‘regressive evolution’ is proposed; a hypothesis linked to possible climatic cooling and presented here on the basis either of new data or in comparison with observed analogies on fossils from Italian and foreign caves.

Abstract This short paper presents a reply on a book review, published for the first time in the April 2005 issue of www.PalArch.nl

Abstract The so–called ‘triple–layered’ enameloid of neoselachian sharks is made of two main units: a superficial one and an internal one including the parallel–bundled enameloid and the tangled–bundled enameloid. The Triassic Synechodontiformes possess a parallel–bundled enameloid in which radial bundles are not very well–developed, contrary to what have been observed in more recent Synechodontiformes and other neoselachian sharks. The well–developed enameloid ridges that ornament the crown of many Synechodontiform sharks are superficial structures and show exactly the same organisation as in the cutting edges of more recent neoselachian sharks. We propose that two different mechanisms lead to the formation of ridges at the surface of the crown in neoselachian shark teeth. Ridges may result from an early mineralisation process during tooth development, or may mineralise near the end of the tooth development. Finally, on the basis of both tooth morphology and enameloid microstructure, the species “Hybodus” minor is transferred into the genus Rhomphaiodon.

Abstract The left front paddle of an unidentified elasmosaurid in the collection of the Fick Fossil and History Museum exhibits two groups of deeply incised grooves across the dorsal and ventral sides of the humerus that suggest a series of bites by the lamniform shark, Cretoxyrhina mantelli. The remains were discovered by George F. Sternberg in 1925 in the Smoky Hill Chalk Member of the Niobrara Chalk, Logan County, Kansas, USA. Archival photographs, along with Sternberg’s hand written note, document the condition of the specimen when originally collected. The specimen is significant because it preserves the first evidence of probable feeding by C. mantelli on an elasmosaurid, and because it represents the rare occurrence of an elasmosaurid in the upper Smoky Hill Chalk of western Kansas.

Abstract Variability of dinosaur eggshell assigned to Megaloolithidae, from the Upper Cretaceous of Suterranya (Upper Campanian–Early Maastrichtian, Catalonia, South–Central Pyrenees), is described and compared with other Catalan, Argentinean, French, and Indian contemporaneous eggshells. Two–variable statistics using eggshell thickness and external diameter of eggshell units show discontinuous heterogeneity in the studied sample. Highly significant, stronger heterogeneity is also observed when comparing eggshell thickness from Suterranya to other neighbouring samples (Basturs, Coll de Nargó, Pioch Herbaut and Les Vignes) and India. Heterogeneity is interpreted as probably indicative of dinosaur polytypic diversity, instead of polymorphism of eggshell from one dinosaurian paleospecies. Variability distribution of eggshell thickness suggests a 15% coefficient of variation as the upper limit of a homogeneous intraspecific eggshell sample. The utility of eggshells as an indicator of nesting dinosaur diversity, particularly in the Catalan Pyrenees, is discussed. + erratum.