New material of Caenagnathasia martinsoni (Dinosauria: Theropoda: Oviraptorosauria) from the Bissekty Formation (Upper Cretaceous: Turonian) of Uzbekistan

2015 ◽  
Vol 54 ◽  
pp. 50-59 ◽  
Author(s):  
Hans-Dieter Sues ◽  
Alexander Averianov
Keyword(s):  
Upper Cretaceous ◽  
New Material

NEW MATERIAL OF SMALL DINOSAURS FROM THE UPPER CRETACEOUS ALLISON MEMBER, MENEFEE FORMATION, NEW MEXICO

2019 ◽  
Author(s):  
Kara A. Kelley ◽  
◽  
Charlotte J.H. Hohman ◽  
Andrew T. McDonald ◽  
Douglas G. Wolfe
Keyword(s):  
New Mexico ◽  
Upper Cretaceous ◽  
New Material

scholarly journals Taming an ichnotaxonomical Pandora's box: revision of dendritic and rosetted microborings (ichnofamily: Dendrinidae)

2017 ◽  
Author(s):  
Max Wisshak
Keyword(s):  
Upper Cretaceous ◽  
Trace Fossils ◽  
Convincing Evidence ◽  
Mass Extinctions ◽  
Noticeable Effect ◽  
Evolutionary Patterns ◽  
Symbiotic Relationships ◽  
New Material ◽  
Adaptive Radiations ◽  
Extinction Events

Dendritic and/or rosetted microborings in calcareous and osteic skeletal substrates have a diverse trace fossil record, spanning most of the Phanerozoic, whereas the ichnodiversity of comparable bioerosion traces produced in modern seas is rather limited. The most prominent occurrences are known from Devonian brachiopods and from Upper Cretaceous belemnite rostra. Ichnotaxonomically, they are comprised within one of the few ichnofamilies established to date, the Dendrinidae Bromley et al., 2007. As an outcome of the present revision of this ichnofamily, the plethora of 84 ichnospecies established within 25 ichnogenera since the erection of the type ichnogenus Dendrina Quenstedt, 1849 was considerably condensed to 22 ichnospecies included in 7 ichnogenera, based on a coherent morphological categorisation and ichnotaxobasis assessment. The suite of ichnogenera now subsumed within the Dendrinidae includes Dendrina Quenstedt, 1849; Clionolithes Clarke, 1908; Calcideletrix Mägdefrau, 1937; Dictyoporus Mägdefrau, 1937; Abeliella Mägdefrau, 1937; Nododendrina Vogel et al., 1987; and Pyrodendrina Tapanila, 2008. New combinations thereby concern Dendrina dendrina (Morris, 1851) comb. nov., Clionolithes pannosus (Solle, 1938) comb. nov., C. alcicornis (Vogel et al., 1987) comb. nov., C. convexus (Hofmann, 1996) comb. nov., Calcideletrix anomala (Mägdefrau, 1937) comb. nov., C. fastigata (Radtke, 1991) comb. nov., Dictyoporus balani (Tavernier et al., 1992) comb. nov., Nododendrina europaea (Fischer, 1875) comb. nov., N. incomposita (Mägdefrau, 1937) comb. nov. and N. paleodendrica (Elias, 1957) comb. nov. Investigation of new material and a reassessment of 63 dendrinid microborings previously addressed in informal nomenclature allowed the establishment of two complementing ichnogenera, Rhopalondendrina igen. nov. and Antodendrina igen. nov., and eight new ichnospecies, comprising Pyrodendrina arctica isp. nov., P. belua isp. nov., P. villosa isp. nov., Rhopalondendrina avis igen. et isp. nov., R. acanthina igen. et isp. nov., R. contra igen. et isp. nov., R. tigris igen. et isp. nov. and Antodendrina ligula igen. et isp. nov. In densely bioeroded calcareous substrates, different dendrinids and other bioerosion traces may be found in direct contact with each other, forming composite trace fossils, but some of these associations appear rather systematic in nature and could be the work of the same tracemaker under different behavioural modes, thus forming compound trace fossils. In these cases, however, the distinction between the two concepts remains largely equivocal. Dendrinid microborings are primarily found in living and dead calcareous skeletal substrates of bivalves, brachiopods, belemnites and corals, with complementing records from six other substrate types. Facing considerable sampling artefacts, evidence for true substrate specificity or symbiotic relationships is inconclusive as yet, whereas there is direct evidence for post-mortem infestation in several cases, such as the diverse dendrinid associations in Upper Cretaceous belemnite guards. Despite a wealth of available interpretations, the actual biological identity of the dendrinids’ tracemakers remains largely speculative. The most convincing evidence has been put forward in support of foraminiferans as the producers of Nododendrina, and excavating micro-sponges producing Clionolithes and some Calcideletrix. Since most of the dendrinids are found in aphotic (palaeo-)environments, these two principal types of organotrophic tracemakers are also potential candidates for the other ichnogenera. With regards to evolutionary patterns through geologic time, strong adaptive radiations are evident from the ichnodiversity of dendrinid ichnospecies in the Early to Mid-Palaeozoic, reflecting the “Ordovician Bioerosion Revolution” (sensu Wilson & Palmer 2006) and the “Mid-Palaeozoic Precursor of the Mesozoic Marine Revolution” (sensu Signor & Brett 1984), respectively, and in the Mesozoic, coinciding with the prominent “Marine Mesozoic Revolution” (sensu Vermeij 1977). This pattern mimics that of other micro- and macro-bioerosion trace fossils and is interpreted as a reflection of increased predation pressure and consequent infaunalisation. For extinction events, in turn, a differential effect is recorded in that the first four of the “Big Five” mass extinctions appear not to have had any noticeable effect on dendrinid ichnodiversity, whereas the end-Cretaceous mass-extinction resulted in a 77% drop following the Cretaceous peak ichnodiversity of 13 dendrinid ichnospecies.

Basal ornithopod (Dinosauria: Ornithischia) teeth from the Prince Creek Formation (early Maastrichtian) of Alaska

2011 ◽  
Vol 48 (9) ◽  
pp. 1342-1354 ◽  
Author(s):  
Caleb Marshall Brown ◽  
Patrick Druckenmiller
Keyword(s):  
Upper Cretaceous ◽  
Cheek Tooth ◽  
North Slope ◽  
Sister Taxon ◽  
Hell Creek Formation ◽  
New Material ◽  
Previous Assignment ◽  
Stratigraphic Range

A diverse and prolific record of polar dinosaurs comes from the Upper Cretaceous (Campanian–Maastrichtian) sediments of the Prince Creek Formation exposed on Alaska’s North Slope. Previous assignment of basal ornithopod material from this formation has been based solely on teeth, which have either been referred to “hypsilophodontid” indet. or Thescelosaurus sp. Here, we re-examine this material and describe several new specimens, including five isolated premaxillary teeth and three cheek teeth. The premaxillary teeth are most similar to those of Thescelosaurus , whereas the cheek teeth are more similar to its sister taxon Parksosaurus , for which premaxillary teeth are unknown. Referral of this new material to Thescelosaurus would represent the oldest occurrence of this taxon and considerably extend its stratigraphic range. A more likely possibility is that the premaxillary teeth are referable to Parksosaurus, an interpretation that is more parsimonious from a stratigraphic perspective. Intriguingly, one cheek tooth previously referred to as “hypsilophodontid” cannot be referred to either Thescelosaurus or Parksosaurus. Previously, faunal comparisons of the Prince Creek Formation have largely been made with non-contemporaneous formations, including the Campanian-aged Judith River and Aguja formations, or to the latest Maastrichtian Hell Creek Formation. On the basis of age and faunal similarities, a more appropriate comparison should be made with coeval rocks of the Horseshoe Canyon. This study expands our knowledge of Cretaceous ornithischian diversity at polar paleolatitudes and underscores the importance of small, rare, or easily misidentified fossils in paleoecological studies.

Postcranial morphology of Aristonectes (Plesiosauria, Elasmosauridae) from the Upper Cretaceous of Patagonia and Antarctica

2012 ◽  
Vol 25 (1) ◽  
pp. 71-82 ◽  
Author(s):  
José P. O'Gorman ◽  
Zulma Gasparini ◽  
Leonardo Salgado
Keyword(s):  
Upper Cretaceous ◽  
South American ◽  
Postcranial Skeleton ◽  
Rio Negro ◽  
Juvenile Individual ◽  
New Material ◽  
Lower Maastrichtian ◽  
First Time ◽  
Upper Maastrichtian ◽  
Upper Campanian

AbstractA partial, postcranial skeleton of a juvenile individual referred to Aristonectes cf. parvidens from the upper Maastrichtian López de Bertodano Formation, Isla Marambio (Seymour Island), Antarctica, is described. Additionally, two juvenile specimens, also referred to A. cf. parvidens from the Allen Formation (upper Campanian–lower Maastrichtian) and Jagüel Formation (upper Maastrichtian) (Río Negro province, Argentina), are redescribed. The analysis of the systematic value of the cervical centrum proportions of juvenile specimens of Elasmosauridae suggests that these elements can be used to differentiate juvenile specimens of A. cf. parvidens from juveniles of other Elasmosauridae. On this basis, the specimens described are referred to A. cf. parvidens. Based on the proportion of the cervical centra, the first South American plesiosaur described by Gay in 1848 is here referred to A. cf. parvidens. The coracoid of Aristonectes is described for the first time showing a cordiform fenestra, a feature only recorded in the Elasmosauridae among the Plesiosauria, therefore, these new data support the inclusion of Aristonectes within the Elasmosauridae. With the new material described in this paper, Aristonectes is one of the most frecuently recorded genera of Late Cretaceous plesiosaurs in the Southern Hemisphere.

New materials of Gasparinisaura cincosaltensis (Ornithischia, Ornithopoda) from the Upper Cretaceous of Argentina

1997 ◽  
Vol 71 (5) ◽  
pp. 933-940 ◽  
Author(s):  
Leonardo Salgado ◽  
Rodolfo A. Coria ◽  
Susana E. Heredia
Keyword(s):  
Phylogenetic Analysis ◽  
Upper Cretaceous ◽  
Nest Site ◽  
New Materials ◽  
Rio Negro ◽  
New Material

New material of Gasparinisaura cincosaltensis from the Río Colorado Formation (Upper Cretaceous) of northwestern Patagonia (Río Negro Province, Argentina) provides seven new characters that are interpreted as autapomorphies of the species: 1) four true sacrals; 2) first sacral rib not coalescent with second sacral rib; 3) long pubic peduncle of ilium; 4) absence of anterior intercondylar groove on femur; 5) both malleoli of the tibia approximately at the same level; 6) metatarsal II posteriorly compressed laterally; and 7) low ascendant process of the astragalus. A phylogenetic analysis of selected ornithopods indicates that Gasparinisaura cincosaltensis is the most plesiomorphic Euiguanodontia. A complete absence of hatchlings indicates that Cinco Saltos was not a nest site.

The titanosaurian dinosaur Atsinganosaurus velauciensis (Sauropoda) from the Upper Cretaceous of southern France: New material, phylogenetic affinities, and palaeobiogeographical implications

2018 ◽  
Vol 91 ◽  
pp. 429-456 ◽  
Author(s):  
Verónica Díez Díaz ◽  
Géraldine Garcia ◽  
Xabier Pereda-Suberbiola ◽  
Benjamin Jentgen-Ceschino ◽  
Koen Stein ◽  
...  
Keyword(s):  
Upper Cretaceous ◽  
Southern France ◽  
New Material ◽  
Phylogenetic Affinities

scholarly journals A small azhdarchoid pterosaur from the latest Cretaceous, the age of flying giants

2016 ◽  
Vol 3 (8) ◽  
pp. 160333 ◽  
Author(s):  
Elizabeth Martin-Silverstone ◽  
Mark P. Witton ◽  
Victoria M. Arbour ◽  
Philip J. Currie
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Fossil Record ◽  
Upper Cretaceous ◽  
Large Species ◽  
Time Of Death ◽  
The West ◽  
New Material ◽  
The Individual ◽  
Continental Interior

Pterosaur fossils from the Campanian–Maastrichtian of North America have been reported from the continental interior, but few have been described from the west coast. The first pterosaur from the Campanian Northumberland Formation (Nanaimo Group) of Hornby Island, British Columbia, is represented here by a humerus, dorsal vertebrae (including three fused notarial vertebrae), and other fragments. The elements have features typical of Azhdarchoidea, an identification consistent with dominance of this group in the latest Cretaceous. The new material is significant for its size and ontogenetic stage: the humerus and vertebrae indicate a wingspan of ca 1.5 m, but histological sections and bone fusions indicate the individual was approaching maturity at time of death. Pterosaurs of this size are exceedingly rare in Upper Cretaceous strata, a phenomenon commonly attributed to smaller pterosaurs becoming extinct in the Late Cretaceous as part of a reduction in pterosaur diversity and disparity. The absence of small juveniles of large species—which must have existed—in the fossil record is evidence of a preservational bias against small pterosaurs in the Late Cretaceous, and caution should be applied to any interpretation of latest Cretaceous pterosaur diversity and success.

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