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[dinosaur] Mesozoic terrestrial vertebrate diversification + Quetzalcoatlus ICZN petition + Brasilichnium tracks

Ben Creisler

Some recent papers:

Free pdf:

Roger A. Close, Roger B.J. Benson, Paul Upchurch & Richard J. Butler (2017)

Controlling for the species-area effect supports constrained long-term Mesozoic terrestrial vertebrate diversification.

Nature Communications 8, Article number: 15381 (2017)




Variation in the geographic spread of fossil localities strongly biases inferences about the evolution of biodiversity, due to the ubiquitous scaling of species richness with area. This obscures answers to key questions, such as how tetrapods attained their tremendous extant diversity. Here, we address this problem by applying sampling standardization methods to spatial regions of equal size, within a global Mesozoic-early Palaeogene data set of non-flying terrestrial tetrapods. We recover no significant increase in species richness between the Late Triassic and the Cretaceous/Palaeogene (K/Pg) boundary, strongly supporting bounded diversification in Mesozoic tetrapods. An abrupt tripling of richness in the earliest Palaeogene suggests that this diversity equilibrium was reset following the K/Pg extinction. Spatial heterogeneity in sampling is among the most important biases of fossil data, but has often been overlooked. Our results indicate that controlling for variance in geographic spread in the fossil record significantly impacts inferred patterns of diversity through time.


Stephen L. Brusatte (2017)

Evolution: Uprooting the Dinosaur Family Tree

Current Biology 27(10): pR390–R392

DOI: http://dx.doi.org/10.1016/j.cub.2017.04.001 |



A provocative new study rearranges the base of the dinosaur evolutionary tree, upending 130 years of consensus. Does it hold up to scrutiny?


Brian Andres, Kevin Padian, Timothy B. Rowe, Christopher J. Bell, Matthew A. Brown, J. Chris Sagebiel, Thomas M. Lehman and James R. Cunningham (2017)

Case 3728 — Quetzalcoatlus northropi (Reptilia, Pterosauria): proposed availability and attribution of authorship to Lawson, 1975.

Bulletin of Zoological Nomenclature 74(1): 34–37

doi: http://dx.doi.org/10.21805/bzn.v74.a010



6. The International Commission on Zoological Nomenclature is accordingly asked:

(1) to use its plenary power to make the following names available:

(a) Quetzalcoatlus Lawson, 1975b as a generic name;

(b) northropi Lawson, 1975b, as published in the binomen Quetzalcoatlus

northropi, as a specific name;

(2) to use its plenary power to attribute authorship and date of Lawson (1975b)

to the following names:

36 Bulletin of Zoological Nomenclature 74 (15 May 2017) ISSN 2057-0570 (online)

(a) Quetzalcoatlus Lawson, 1975b as a generic name;

(b) northropi Lawson, 1975b, as published in the binomen Quetzalcoatlus

northropi, as a specific name;

(3) to place on the Official List of Generic Names in Zoology the name

Quetzalcoatlus Lawson, 1975b (gender masculine), type species by monotypy

Quetzalcoatlus northropi Lawson, 1975b;

(4) to place on the Official List of Specific Names in Zoology the name northropi

Lawson, 1975b as published in the binomen Quetzalcoatlus northropi.


Kenneth Carpenter (2017)

Comment (Case 3700) — Opposition against the proposed designation of Diplodocus carnegii Hatcher, 1901 as the type species of Diplodocus Marsh, 1878 (Dinosauria, Sauropoda).

Bulletin of Zoological Nomenclature 74(1): 47–49

doi: http://dx.doi.org/10.21805/bzn.v74.a014


From the text:

Finally, Tschopp & Mateus (2016) have stated that changing the holotype of Diplodocus longus to Diplodocus carnegii has precedent with the changing of types for several dinosaurs. For example, the change of the type species of Stegosaurus armatus for Stegosaurus stenops by Galton (2011). However, having been involved in the first detailed description and illustration of the holotype, S. armatus (Carpenter & Galton 2001), the two cases have significant differences. None of the bones of S. armatus are complete and no other material is or was available from holotype quarry for reference. This is not the case for D. longus in which many additional specimens, including skulls, were available for Marsh to supplement his later descriptions (e.g., Marsh, 1896b). The problem as Gilmore (1932: 8) astutely observed is that “... the species D. carnegii is … without specific characterization. Whether this species can be satisfactorily maintained, only a restudy of the original materials can determine”. It was precisely such a restudy that McIntosh and I were undertaking when he passed away. The specimen based phylogenetic analysis of diplodocid by Tschopp et al. (2015) was an important contribution as a testable hypothesis for relationships, but the terminal position of so many specimens should have caused them to question whether their rigid, mechanistic results were realistic. There is certainly no justifiable reason for replacing D. longus with D. carnegii except for the convenience of their analysis. 



Free pdf:

George F. Engelmann and Daniel J. Chure (2017)

Morphology and sediment deformation of downslope Brasilichnium trackways on a dune slipface in the Nugget Sandstone of northeastern Utah, USA.

Palaeontologia Electronica 20.2.22A: 1-21 

doi:  palaeo-electronica.org/content/2017/1845-downslope-trackways


The presumed synapsid trackway known as Brasilichnium is known by numerous trackways from many localities throughout the eolian deposits of the Late Triassic to Early Jurassic erg that covered much of the western United States. These trackways occur primarily on the foreset beds of dunes. The overwhelming majority of the trackways were made by animals traveling up slope. A slab of Nugget Sandstone exhibited in the Department of Geology and Geophysics at the University of Utah preserves at least 17 Brasilichnium trackways, 13 going up slope and four going down slope. The downslope tracks have a distinctive morphology consisting of a raised anterior pressure pad ahead of, and a posterior collapse depression behind, a small, poorly preserved impression of the foot. The anterior pressure pad can be explained as a low angle thrust driven forward by the impact of the foot, whereas the posterior depression is a downslope slump as the foot was withdrawn. This interpretation is supported by the observation on an outcrop in Dinosaur National Monument of similar features in a Brasilichnium trackway that traverses the slope, and by studies of tracks made by other vertebrates in eolian sands. The enormous preponderance of upslope over downslope trackways in eolian sandstones remains an open question. The distinctiveness of the downslope track morphology and the fact that they are well preserved in the studied material, however, suggests that the answer is something more than coincidence or preservation bias.