A Centrosaurine (Dinosauria: Ceratopsia) from the Aguja Formation (Late Campanian) of Northern Coahuila, Mexico

Abstract

While centrosaurines and ceratopsids in general are abundant in the Late Campanian of northern Laramidia, they are much less commonly found in southern Laramidia. This has supported hypotheses of dinosaur provinciality and endemism in the Late Cretaceous with the delineation of at least two separate faunal zones, north and south Laramidia. There have been 12 genera of centrosaurines recognized from northern Laramidia while two genera, Diabloceratops and Nasutoceratops, have been named from southern Laramidia. We present an osteological description and taphonomic outline for a new centrosaurine ceratopsid from the Aguja Formation of northern Coahuila, Mexico that is not currently diagnosable to the generic level, but likely represents a new taxon. Further, we have included three-dimensional surface scans of all material attributed to this animal. Considering the large number of centrosaurines from northern Laramidia, it is likely that cladistic analyses are biased towards this faunal zone. New findings of southern centrosaurines are needed to correct this bias. This discovery expands the range of centrosaurines south to Coahuila, Mexico and adds new information to better characterize the morphology and taxonomy of centrosaurines from southern Laramidia and their evolution in comparison to their northern counterparts.

Palaeoenvironmental drivers of vertebrate community composition in the Belly River Group (Campanian) of Alberta, Canada, with implications for dinosaur biogeography

“…It is also possible that the palaeoenvironmental interpretation of these formations and sampling areas is more complex than originally described [50], though, pending future geological revisions, there is currently no reason to think this is the case. The relative similarity of the dinosaur faunal assemblages of DPP and MRM, and how those contrast to the differences seen in the rest of the vertebrate faunal assemblage between these areas and throughout the extent of the Belly River Group, runs counter to the long-standing idea that dinosaurs, including large bodied taxa like hadrosaurs and ceratopsians, are sensitive to relatively small environmental changes across the palaeolandscape, and that this sensitivity is the cause of the large diversity of geographically or formationally restricted taxa known from the Late Cretaceous of western North America [1–8, 11, 19–24, 27, 39, 43, 70]. …”

“…The sensitivity of dinosaur populations to changes in altitudinal (distance from palaeoshoreline) and latitudinal environmental gradients has been the subject of considerable debate for over 30 years [1–9, 11, 15, 23, 26, 27, 42–46, 55, 62, 70], and though it has been questioned [17, 18, 22, 28, 74], it remains one of the primary explanations for patterns observed in the evolution and distribution of dinosaurs throughout the Late Cretaceous of western North America. A focused sub-sampling of the time-equivalent interval of the Oldman and Dinosaur Park formations within the larger Belly River Group microsite abundance dataset facilitates a controlled and direct test of dinosaur assemblage changes across differing palaeoenvironments (Figs.…”

“…We also hypothesize that dinosaurs, particularly those of large body size, will not be sensitive to altitudinal change as recorded in the Belly River Group. This hypothesis is based on the resilience to environmental variation and broad latitudinal distributions seen in many groups of large mammals today [2, 7, 32], though it is at odds with much of the literature on dinosaur environmental associations [1–9, 11, 14, 15, 19–24, 26, 27, 42, 43, 62]. …”

The first reported ceratopsid dinosaur from eastern North America (Owl Creek Formation, Upper Cretaceous, Mississippi, USA)

“…A major unconformity is recognized at the base of the Chiwapa Sandstone, separating it from the remainder of the subjacent Ripley Formation. Contrary to the age of the sub-Chiwapa Ripley given here (early Maastrichtian), foraminiferal zonation established for the Gulf Coast by Mancini et al (1995) and Puckett (2005) Ceratopsid occurrences and their associated ages are taken from numerous references (Lehman, 1996;Sullivan, Boere & Lucas, 2005;Loewen et al, 2010;Sampson et al, 2010Sampson et al, , 2013Sullivan & Lucas, 2010;Porras-Múzquiz & Lehman, 2011;Wick & Lehman, 2013;Rivera-Sylva, Hedrick & Dodson, 2016;Lehman, Wick & Barnes, 2016). Arrows designate late Maastrichtian dispersal of ceratopsians, in this interpretation, along an emerging southern route formed by a northerly retreating seaway.…”

Peer Review #1 of "The first reported ceratopsid dinosaur from eastern North America (Owl Creek Formation, Upper Cretaceous, Mississippi, USA) (v0.1)"

“…Late Campanian (left) and late Maastrichtian (right) time slices are depicted with southern Laramidia ceratopsid localities on the appropriate time interval map. Ceratopsid occurrences and their associated ages are taken from numerous references (Lehman, 1996;Sullivan, Boere & Lucas, 2005;Loewen et al, 2010;Sampson et al, 2010Sampson et al, , 2013Sullivan & Lucas, 2010;Porras-Múzquiz & Lehman, 2011;Wick & Lehman, 2013;Rivera-Sylva, Hedrick & Dodson, 2016;Lehman, Wick & Barnes, 2016). Arrows designate late Maastrichtian dispersal of ceratopsians, in this interpretation, along an emerging southern route formed by a northerly retreating seaway.…”