Troodontids (Theropoda) from the Dinosaur Park Formation, Alberta, with a description of a unique new taxon: implications for deinonychosaur diversity in North America

2017 ◽  
Vol 54 (9) ◽  
pp. 919-935 ◽  
Author(s):  
Aaron J. van der Reest ◽  
Philip J. Currie
Keyword(s):  
North America ◽  
North American ◽  
New Taxon ◽  
Ventral Margin ◽  
Hind Limbs ◽  
Dinosaur Park Formation ◽  
Upper Campanian ◽  
Partial Skeleton

Troodontids are known from Asia and North America, with the most complete specimens from the Jurassic of China and the Cretaceous of Mongolia. North American troodontids are poorly known, and specimens that have been described are isolated elements or partial skeletons with limited material. A new troodontid from the upper Dinosaur Park Formation (upper Campanian) is based on partial skulls, several vertebrae, ribs, gastralia, chevrons, a sacrum, partial pelvis, and partial fore and hind limbs. It is the largest troodontid known, with an estimated height of 180 cm and length of 350 cm. Like other troodontids, it possesses an elongated ambiens process and has a horizontal ventral margin of the postacetabular process. It differs from all other derived troodontids in that the slightly retroverted pubis has a shaft that curves anteroventrally. Some specimens from the Dinosaur Park Formation previously assigned to Troodon are reassigned to the new taxon, including multiple partial crania, an associated dentary and metatarsus, and a partial skeleton. Previously undescribed elements from the lower part of the Dinosaur Park Formation are assigned to the resurrected Stenonychosaurus inequalis. Distinct stratigraphic separation of Stenonychosaurus inequalis and the new taxon indicates a replacement in troodontid fauna, similar to the turnover of large ornithischians in the same formation. The new taxon is phylogenetically more closely related to Mongolian taxa, indicating the replacement of Stenonychosaurus may have been from an earlier Asian form immigrating into North America.

An ornithurine bird coracoid from the Late Cretaceous of Alberta, Canada

2020 ◽  
pp. 1-7
Author(s):  
Sydney R. Mohr ◽  
John H. Acorn ◽  
Gregory F. Funston ◽  
Philip J. Currie
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Ct Scans ◽  
Micro Ct ◽  
Internal Structures ◽  
Postcranial Remains ◽  
Dinosaur Park Formation ◽  
Upper Campanian

The Cretaceous birds of Alberta are poorly known, as skeletal elements are rare and typically consist of fragmentary postcranial remains. A partial avian coracoid from the upper Campanian Dinosaur Park Formation of Alberta, Canada, can be referred to the Ornithurae, and is referred to here as Ornithurine G (cf. Cimolopteryx). Its structure is similar to previously described ornithurine coracoids from Alberta and other localities in North America, particularly those belonging to the genus Cimolopteryx. A comparison of these elements indicates that the new coracoid is distinct; however, its preservation prevents complete diagnosis. As other Cimolopteryx are Maastrichtian in age, Ornithurine G (cf. Cimolopteryx) also represents the earliest occurrence of a Cimolopteryx-like anatomy. A pneumatized coracoid is a diagnostic trait of Neornithes, identified by the presence of a pneumatic foramen. Ornithurine G (cf. Cimolopteryx) does not preserve this feature. CT and micro-CT scans of both pneumatic and apneumatic coracoids of modern birds show similar internal structures to Ornithurine G (cf. Cimolopteryx), indicating that pneumaticity of the coracoid cannot be determined in the absence of an external pneumatic foramen. A comparison between members of Cimolopterygidae, including Cimolopteryx and Lamarqueavis, raises questions about the assignment of Lamarqueavis to the Cimolopterygidae, and the validity of this family as a whole.

scholarly journals A new species of troodontid theropod (Dinosauria: Maniraptora) from the Horseshoe Canyon Formation (Maastrichtian) of Alberta, Canada

2017 ◽  
Vol 54 (8) ◽  
pp. 813-826 ◽  
Author(s):  
David C. Evans ◽  
Thomas M. Cullen ◽  
Derek W. Larson ◽  
Adam Rego
Keyword(s):  
New Species ◽  
North America ◽  
Alpha Diversity ◽  
Width Ratio ◽  
New Taxon ◽  
Lateral Region ◽  
Morphometric Analyses ◽  
Dinosaur Park Formation ◽  
Horseshoe Canyon Formation ◽  
A New Species

Troodontid material from the Maastrichtian of North America is extremely rare, beyond isolated teeth from microvertebrate sites. Here we describe troodontid frontals from the early Maastrichtian Horseshoe Canyon Formation (Horsethief Member). The most complete specimen, TMP 1993.105.0001, is notably foreshortened and robust when compared with numerous specimens referred to Troodon from the Dinosaur Park Formation, and exhibits several characteristics that distinguish it from other Late Cretaceous troodontids. Morphometric analyses reinforce shape differences between TMP 1993.105.0001 and other North American troodontids, and show that proportional differences are independent of size. We therefore erect a new taxon, Albertavenator curriei gen. et sp. nov., which is diagnosed by the following autapomorphies: (1) primary supraciliary foramen is truncated anteriorly by the lacrimal contact; (2) superficial (ectocranial) surface of the frontal proportionally shorter than all known troodontids, with a length to width ratio under 1.3; and (3) frontoparietal contact in which an enlarged lappet of the frontal extends medially to extensively overlap the lateral region of the anteromedial process of the parietal. Interestingly, tooth and jaw morphology from the single relatively complete dentary recovered from the Horseshoe Canyon cannot be distinguished from dentaries and teeth from the Dinosaur Park Formation. If the dentary and teeth from the Horsethief Member of the Horseshoe Canyon Formation prove to belong to A. curriei, extensive overlap in tooth morphology between the Dinosaur Park and Horseshoe Canyon formations reinforces the notion that tooth morphotypes do not exhibit strong correspondence to species alpha diversity, and may encompass multiple closely related taxa.

scholarly journals A new species of troodontid theropod (Dinosauria: Maniraptora) from the Horseshoe Canyon Formation (Maastrichtian) of Alberta, Canada

2018 ◽  
Author(s):  
David Evans ◽  
Thomas Cullen ◽  
Derek Larson ◽  
Adam Rego
Keyword(s):  
New Species ◽  
North America ◽  
Alpha Diversity ◽  
Width Ratio ◽  
New Taxon ◽  
Lateral Region ◽  
Morphometric Analyses ◽  
Dinosaur Park Formation ◽  
Horseshoe Canyon Formation ◽  
A New Species

Troodontid material from the Maastrichtian of North America is extremely rare, beyond isolated teeth from microvertebrate sites. Here we describe troodontid frontals from the early Maastrichtian Horseshoe Canyon Formation (Horsethief Member). The most complete specimen, TMP 1993.105.0001, is notably foreshortened and robust when compared with numerous specimens referred to Troodon from the Dinosaur Park Formation, and exhibits several characteristics that distinguish it from other Late Cretaceous troodontids. Morphometric analyses reinforce shape differences between TMP 1993.105.0001 and other North American troodontids, and show that proportional differences are independent of size. We therefore erect a new taxon, Albertavenator curriei gen. et sp. nov., which is diagnosed by the following autapomorphies: (1) primary supraciliary foramen is truncated anteriorly by the lacrimal contact; (2) superficial (ectocranial) surface of the frontal proportionally shorter than all known troodontids, with a length to width ratio under 1.3; and (3) frontoparietal contact in which an enlarged lappet of the frontal extends medially to extensively overlap the lateral region of the anteromedial process of the parietal. Interestingly, tooth and jaw morphology from the single relatively complete dentary recovered from the Horseshoe Canyon cannot be distinguished from dentaries and teeth from the Dinosaur Park Formation. If the dentary and teeth from the Horsethief Member of the Horseshoe Canyon Formation prove to belong to A. curriei, extensive overlap in tooth morphology between the Dinosaur Park and Horseshoe Canyon formations reinforces the notion that tooth morphotypes do not exhibit strong correspondence to species alpha diversity, and may encompass multiple closely related taxa.

Probable deinonychosaur tracks from the Upper Cretaceous Wapiti Formation (upper Campanian) of Alberta, Canada

2020 ◽  
pp. 1-14
Author(s):  
Nathan J. Enriquez ◽  
Nicolás E. Campione ◽  
Corwin Sullivan ◽  
Matthew Vavrek ◽  
Robin L. Sissons ◽  
...  
Keyword(s):  
North America ◽  
Early Cretaceous ◽  
Late Cretaceous ◽  
North American ◽  
Upper Cretaceous ◽  
Temporal Window ◽  
Track Record ◽  
Important Addition ◽  
Additional Support ◽  
Upper Campanian

Abstract Late Cretaceous tracks attributable to deinonychosaurs in North America are rare, with only one occurrence of Menglongipus from Alaska and two possible, but indeterminate, occurrences reported from Mexico. Here we describe the first probable deinonychosaur tracks from Canada: a possible trackway and one isolated track on a single horizon from the Upper Cretaceous Wapiti Formation (upper Campanian) near Grande Prairie in Alberta. The presence of a relatively short digit IV differentiates these from argued dromaeosaurid tracks, suggesting the trackmaker was more likely a troodontid. Other noted characteristics of the Wapiti specimens include a rounded heel margin, the absence of a digit II proximal pad impression, and a broad, elliptical digit III. Monodactyl tracks occur in association with the didactyl tracks, mirroring similar discoveries from the Early Cretaceous Epoch of China, providing additional support for their interpretation as deinonychosaurian traces. Although we refrain from assigning the new Wapiti specimens to any ichnotaxon because of their relatively poor undertrack preservation, this discovery is an important addition to the deinonychosaur track record; it helps to fill a poorly represented geographic and temporal window in their known distribution, and demonstrates the presence of a greater North American deinonychosaur ichnodiversity than has previously been recognized.

The oldest known North American occurrence of the Plesiosauria (Reptilia: Sauropterygia) from the Liassic (Lower Jurassic) Fernie Group, Alberta, Canada

1976 ◽  
Vol 13 (1) ◽  
pp. 185-188 ◽  
Author(s):  
Elizabeth L. Nicholls
Keyword(s):  
North America ◽  
North American ◽  
Lower Jurassic ◽  
Partial Skeleton

A partial skeleton of a plesiosaur, referable to the Plesiosauridae, from the lower Fernie Group (Sinemurian, Lower Jurassic) of Alberta is the oldest known occurrence of the Plesiosauria in North America.

scholarly journals A critical new ankylosaur specimen from the Wessex Formation of the Isle of Wight

2015 ◽  
Author(s):  
Stuart Pond ◽  
Sarah Strachan ◽  
Darren Naish ◽  
Martin Simpson
Keyword(s):  
North America ◽  
Early Cretaceous ◽  
Lower Cretaceous ◽  
New Taxon ◽  
Isle Of Wight ◽  
Close Relatives ◽  
The Uk ◽  
Partial Skeleton

Ankylosaurs (Dinosauria, Ankylosauria) have been known from the Lower Cretaceous English Wealden for over 170 years. Three Wealden ankylosaurian species are currently recognised: Hylaeosaurus armatus and Polacanthus rudgwickensis from the Wealden Sub-basin of Sussex, and Polacanthus foxii from both the Wessex Sub-basin of the Isle of Wight and the Wealden Sub-basin. Within recent years all have been interpreted as close relatives within the clade Polacanthidae or Polacanthinae, the monophyly of which is controversial. Most views of polacanthines as a whole are based on substantially better remains from North America. Despite the familiarity of Hylaeosaurus and Polacanthus, many questions remain about their anatomy, taxonomy and relationships and a thorough re-appraisal of the British taxa are needed. We discuss a new ankylosaur discovered in 1994 in the Wessex Formation at Chilton Chine, Isle of Wight. This partial skeleton (including limb and limb girdle elements, vertebrae and osteoderms) is one of the most complete ankylosaurs ever found in the UK and has the potential to resolve many questions about these dinosaurs. It has been provisionally referred to P. foxii but differs in several respects from the holotype and referred specimens of this taxon. Each bone has been recorded using photogrammetry and we have reconstructed the skeleton in 3D. The histology of the sacral shield shows a plywood-like structure with extensive, well ordered structural fibres, in contrast to previously reported Polacanthus specimens. Initial findings suggest that the specimen represents a new taxon. Its implications for Early Cretaceous ankylosaur diversity and taxonomy will be discussed.

scholarly journals A critical new ankylosaur specimen from the Wessex Formation of the Isle of Wight

2015 ◽  
Author(s):  
Stuart Pond ◽  
Sarah Strachan ◽  
Darren Naish ◽  
Martin Simpson
Keyword(s):  
North America ◽  
Early Cretaceous ◽  
Lower Cretaceous ◽  
New Taxon ◽  
Isle Of Wight ◽  
Close Relatives ◽  
The Uk ◽  
Partial Skeleton

Ankylosaurs (Dinosauria, Ankylosauria) have been known from the Lower Cretaceous English Wealden for over 170 years. Three Wealden ankylosaurian species are currently recognised: Hylaeosaurus armatus and Polacanthus rudgwickensis from the Wealden Sub-basin of Sussex, and Polacanthus foxii from both the Wessex Sub-basin of the Isle of Wight and the Wealden Sub-basin. Within recent years all have been interpreted as close relatives within the clade Polacanthidae or Polacanthinae, the monophyly of which is controversial. Most views of polacanthines as a whole are based on substantially better remains from North America. Despite the familiarity of Hylaeosaurus and Polacanthus, many questions remain about their anatomy, taxonomy and relationships and a thorough re-appraisal of the British taxa are needed. We discuss a new ankylosaur discovered in 1994 in the Wessex Formation at Chilton Chine, Isle of Wight. This partial skeleton (including limb and limb girdle elements, vertebrae and osteoderms) is one of the most complete ankylosaurs ever found in the UK and has the potential to resolve many questions about these dinosaurs. It has been provisionally referred to P. foxii but differs in several respects from the holotype and referred specimens of this taxon. Each bone has been recorded using photogrammetry and we have reconstructed the skeleton in 3D. The histology of the sacral shield shows a plywood-like structure with extensive, well ordered structural fibres, in contrast to previously reported Polacanthus specimens. Initial findings suggest that the specimen represents a new taxon. Its implications for Early Cretaceous ankylosaur diversity and taxonomy will be discussed.

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