A review of nonmarine turtles from the Late Cretaceous of Alberta

2003 ◽  
Vol 40 (4) ◽  
pp. 557-571 ◽  
Author(s):  
Donald B Brinkman
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Geographic Area ◽  
Hell Creek Formation ◽  
Diversity Gradient ◽  
The Family ◽  
Group A ◽  
Dinosaur Park Formation ◽  
Milk River Formation ◽  
Horseshoe Canyon Formation

The Late Cretaceous of Alberta preserves one of the most complete records of fossil turtles within a single geographic area in North America. The Cenomanian Dunvegan Formation contains the earliest record of the family Trionychidae in North America. The Santonian Milk River Formation contains a minimum of ten taxa with Adocus, a small trionychid, and a member of the Solemydidae being the most abundant. Diversity remains high in the mid-Campanian Judith River Group. The solemyidid last occurs in the basal beds of the Judith River Group. A member of the Macrobaenidae first occurs in the Dinosaur Park Formation, the uppermost formation in the Judith River Group. Turtles diversity is low in the late Campanian lower Horseshoe Canyon Formation, and they are absent in the early Maastrichtian upper Horseshoe Canyon Formation. Diversity increases in the late Maastrichtian Scollard Formation, although it is much less than in the contemporaneous Hell Creek Formation of Montana. Two of the taxa present in the Scollard Formation, Compsemys and Plastomenus, occur in late Campanian or early Maastrichtian formations in more southerly areas of North America. The changes in turtle diversity through the Campanian and Maastrichtian are interpreted as a result of shifts in a latitudinal turtle diversity gradient resulting from changes in climate. Based on this interpretation a decrease in temperature from the mid-Campanian to early Maastrichtian, followed by a rapid increase at the beginning of the late Maastrichtian is supported.

First report of protoceratopsians (Neoceratopsia) from the Late Cretaceous Judith River Group, Alberta, Canada

1998 ◽  
Vol 35 (7) ◽  
pp. 820-826 ◽  
Author(s):  
Michael J Ryan ◽  
Philip J Currie
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Fossil Record ◽  
Coastal Environments ◽  
First Report ◽  
Skeletal Material ◽  
First Occurrence ◽  
Dinosaur Park Formation ◽  
Milk River Formation

Protoceratopsians are best known in North America from associated skeletal material of Montanoceratops from the early Maastrichtian of Montana and Campanian of Alberta and Leptoceratops from the late Maastrichtian of Alberta and Wyoming. We report here the first occurrence of protoceratopsian elements from the middle Campanian (Dinosaur Park Formation) of Alberta. The specimens consist of a fragmentary right dentary and an almost complete left dentary which can be referred to Leptoceratops sp. Recent examination of Albertan microvertebrate material has identified cf. protoceratopsians teeth from the latest Santonian (Milk River Formation), extending the record of Albertan protoceratopsians back almost 20 million years. The rarity of these small ornithischians in the fossil record of Alberta may have been due to ecological exclusion from the wet, coastal environments that were preferred by the larger, more abundant ceratopsids.

A new articulated freshwater fish (Clupeomorpha, Ellimmichthyiformes) from the Horseshoe Canyon Formation, Maastrichtian, of Alberta, CanadaThis article is one of a series of papers published in this Special Issue on the theme Albertosaurus.

2010 ◽  
Vol 47 (9) ◽  
pp. 1183-1196 ◽  
Author(s):  
Michael G. Newbrey ◽  
Alison M. Murray ◽  
Donald B. Brinkman ◽  
Mark V. H. Wilson ◽  
Andrew G. Neuman
Keyword(s):  
North America ◽  
Posterior Margin ◽  
Upper Cretaceous ◽  
New Genus ◽  
Special Issue ◽  
New Genus And Species ◽  
Sensory Canal ◽  
The Family ◽  
Milk River Formation ◽  
Horseshoe Canyon Formation

Horseshoeichthys armaserratus , gen. et sp. nov., (Clupeomorpha: Ellimmichthyiformes: Sorbinichthyidae) is described from the Horseshoe Canyon Formation (Maastrichtian), Albertosaurus bonebed locality, Alberta, Canada. Horseshoeichthys armaserratus is classified as an ellimmichthyiform based on the following characters: the presence of a sixth infraorbital with a sensory canal that leads to the fifth infraorbital, absence of a supraorbital bone, subrectangular predorsal scutes, parietals in contact with each other at the midline, and two supramaxillae. The specimen is classified in the Sorbinichthyidae Family as it has abdominal ribs articulating in pits on the centra, posterior spines on predorsal scutes, and absence of a median spine on predorsal scutes. A new genus and species is proposed based on the presence of (anteriorly) Y-shaped mesethmoid, supraorbital, subrectangular predorsal scutes with coarse, rounded serrae on the posterior margin and a large anterior projection, scales with serrae on the circuli, and two postcleithra. This specimen represents the first freshwater ellimmichthyiform from the Upper Cretaceous of North America and the highest paleolatitude (59°N) occurrence known for the family. Furthermore, the dentary and centra have distinctive morphologies that are matched by specimens in microvertebrate localities from three underlying formations, including the Milk River Formation (Santonian), which indicates at least a 14 million year history for this lineage.

scholarly journals The Dakoticancridae (Decapoda, Brachyura) from the Late Cretaceous of North America and Mexico

1998 ◽  
Vol 67 (4) ◽  
pp. 237-255 ◽  
Author(s):  
G.A. Bishop ◽  
R.M. Feldmann ◽  
F. Vega
Keyword(s):  
North America ◽  
Functional Morphology ◽  
Late Cretaceous ◽  
Cladistic Analysis ◽  
Low Level ◽  
The Family

The podotrematous crab family Dakoticancridae includes four genera: Dakoticancer Rathbun, Tetracarcinus Weller, Avitelmessus Rathbun, and Seorsus Bishop, all known solely from the Late Cretaceous of North America. Lathelicocarcinus Bishop, originally referred to the family, must be reassigned. Fine details of anatomy, preserved on specimens of D. overanus Rathbun and A. grapsoideus Rathbun, permit description of genital openings and interpretation of functional morphology of appendages. Although one species, D. australis Rathbun, has been found associated with burrow structures, all were probably vagrant epifaunal animals on fine- to medium-grained siliciclastic substrata. Food was probably obtained by generalized low-level predation and scavenging. Results of a cladistic analysis are consistent with the stratigraphic data suggesting that T. subquadrata Weller is nearest the rootstock of the family and that other taxa within the family are derived from it.

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.

?Tethyaster albertensis, a Late Cretaceous (Turonian) sea star from the Cardium Formation, Alberta, Canada

1990 ◽  
Vol 64 (6) ◽  
pp. 1045-1049 ◽  
Author(s):  
Russell L. Hall ◽  
Suzan Moore
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Sea Star ◽  
Sea Stars ◽  
Peace River ◽  
The North ◽  
The Family ◽  
Cardium Formation ◽  
Northern Alberta ◽  
Limited Change

Although many of the surviving lineages of sea stars appeared during an early Mesozoic radiation of the class and have undergone limited change since then, they have left a very poor fossil record, particularly in the Mesozoic of North America (Blake, 1981). This record from the Late Cretaceous of Alberta is made more significant by the fact that it is apparently only the second occurrence of a member of the family Astropectinidae in the Cretaceous of North America; Lophidiaster silentiensis was described by McLearn (1944) from the Lower Cretaceous (Albian) Hasler Formation, from a now-submerged locality on the Peace River in northern Alberta. All previously recorded fossil sea stars from the North American Cretaceous are representatives of the family Goniasteridae.

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.

Species composition of the Late Cretaceous eutherian mammal Paranyctoides Fox

2013 ◽  
Vol 50 (7) ◽  
pp. 693-700 ◽  
Author(s):  
Marisol Montellano-Ballesteros ◽  
Richard C. Fox ◽  
Craig S. Scott
Keyword(s):  
North America ◽  
Species Composition ◽  
Central Asia ◽  
Late Cretaceous ◽  
Geographic Range ◽  
Eutherian Mammal ◽  
The Past ◽  
Central Asian ◽  
Dinosaur Park Formation ◽  
Eutherian Evolution

Although the known record of Mesozoic eutherian mammals has been significantly enriched in recent years, early eutherian evolution is still not well understood. Among the more controversial of Mesozoic eutherians is Paranyctoides Fox, which was described in 1979 from the Judithian Dinosaur Park Formation, Alberta, Canada. It is a rare taxon and therefore has been identified in only a few other North American Late Cretaceous local faunas since. Within the past decade, dental and gnathic remains discovered in Central Asia have also been referred to Paranyctoides, thereby expanding the geographic range of the genus substantially and making it the only Late Cretaceous eutherian ostensibly occurring in both continents. As a result of our detailed study of Paranyctoides, however, we find that the Central Asian species lack the diagnostic characters of Paranyctoides and must be referred to other taxa. We conclude that this genus was limited to North America, ranging from Aquilan to Lancian time, and accordingly we recognize as valid only the following species: Paranyctoides sternbergi (Judithian, Alberta), P. maleficus (Aquilan, Alberta), Paranyctoides Wahweap sp. A and sp. B (Judithian, Utah), Paranyctoides Kaiparowits sp. A and sp. B (Judithian, Utah). Another purported species of Paranyctoides, P. megakeros, from the Lancian of Wyoming, is a junior synonym of Alostera saskatchewanensis.

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.

scholarly journals Competition structured a Late Cretaceous megaherbivorous dinosaur assemblage

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jordan C. Mallon
Keyword(s):  
Late Cretaceous ◽  
Species Turnover ◽  
Meta Analysis ◽  
Resource Limitation ◽  
Western North America ◽  
The Family ◽  
Structural Principles ◽  
Dinosaur Park Formation ◽  
Upper Campanian

Abstract Modern megaherbivore community richness is limited by bottom-up controls, such as resource limitation and resultant dietary competition. However, the extent to which these same controls impacted the richness of fossil megaherbivore communities is poorly understood. The present study investigates the matter with reference to the megaherbivorous dinosaur assemblage from the middle to upper Campanian Dinosaur Park Formation of Alberta, Canada. Using a meta-analysis of 21 ecomorphological variables measured across 14 genera, contemporaneous taxa are demonstrably well-separated in ecomorphospace at the family/subfamily level. Moreover, this pattern is persistent through the approximately 1.5 Myr timespan of the formation, despite continual species turnover, indicative of underlying structural principles imposed by long-term ecological competition. After considering the implications of ecomorphology for megaherbivorous dinosaur diet, it is concluded that competition structured comparable megaherbivorous dinosaur communities throughout the Late Cretaceous of western North America.

New material of Gilmoremys lancensis nov. comb. (Testudines: Trionychidae) from the Hell Creek Formation and the diagnosis of plastomenid turtles

2011 ◽  
Vol 85 (3) ◽  
pp. 442-459 ◽  
Author(s):  
Walter G. Joyce ◽  
Tyler R. Lyson
Keyword(s):  
Phylogenetic Analysis ◽  
North America ◽  
North Dakota ◽  
Late Cretaceous ◽  
Hell Creek Formation ◽  
Secondary Palate ◽  
New Material

Plastomenidae is a poorly diagnosed clade of extinct soft-shelled turtles (Trionychidae) known from the Campanian to Eocene of North America. Five skulls, a mandible, two carapaces, and numerous plastral remains from the Hell Creek Formation (Late Cretaceous, Maastrichtian) of North Dakota and Montana are referable to Gilmoremys lancensis nov. comb., a taxon previously known from a carapace and xiphiplastron only. Gilmoremys lancensis is diagnosed by a carapace that is covered by elongate sinusoidal grooves, distally expanded second costals, hyoplastral shoulders, an extensive secondary palate with accessory ridges, an extremely elongate mandible, a contribution of the parietal to the wall of the orbit, and a posterior ossified narial canal. A phylogenetic analysis of all well-known plastomenid turtles establishes Gilmoremys lancensis as the most basal known plastomenid and reveals that cranial characters are more reliable in diagnosing plastomenid turtles, in particular the contribution of the parietal to the orbit wall and the extensive secondary palate. All plastomenid turtles with a locked entoplastron are placed in Hutchemys. Assuming that all taxa are monophyletic, the phylogenetic analysis implies that the G. lancensis lineage is the only one to go extinct at the K/T boundary, whereas the four remaining plastomenid lineages survive. Extensive ghost ranges are nevertheless apparent. Taphonomic considerations indicate that G. lancensis was a riverine turtle, whereas more derived plastomenids preferred swampy habitats.

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