[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

New Docodon (Jurassic mammaliaform) species + other non-dino papers



From: Ben Creisler
bcreisler@gmail.com

A number of recent papers:

Guillermo W. Rougier, Amir S. Sheth, Kenneth Carpenter, Lucas
Appella-Guiscafre & Brian M. Davis (2014)
A New Species of Docodon (Mammaliaformes: Docodonta) from the Upper
Jurassic Morrison Formation and a Reassessment of Selected
Craniodental Characters in Basal Mammaliaforms.
Journal of Mammalian Evolution (advance online publication)
DOI: 10.1007/s10914-014-9263-8
http://link.springer.com/article/10.1007/s10914-014-9263-8

We describe a new species of the basal mammaliaform Docodon, D.
apoxys, sp. nov., represented by three nearly complete dentaries from
the Upper Jurassic Morrison Formation of central Colorado. This
species differs from other known species of Docodon in the relative
heights of the principal molar cusps and in the size of the distal
molars. In addition, we attribute a partial rostrum preserving much of
the maxilla and most of the premaxilla, bearing a complete incisor and
premolar count, to Docodon sp. These materials supply previously
unknown morphology for this classic North American Jurassic taxon, and
help establish a common morphology for Docodonta as a whole. While
Docodon differs from the Portuguese docodont Haldanodon in the
presence of only five upper incisors (none of which is entirely within
the maxilla), an internarial bar is present in both taxa. The new
specimens also unambiguously preserve a complete and undistorted
angular process that differs conspicuously from the classical
interpretation of the holotype of Docodon victor; this structure in
docodonts closely resembles the angular process in australosphenidans
and trechnotheres. We abandon the concept of a “pseudangular” process
and we consider the angular process to be a homologous feature (where
present) across Mammaliaformes.

==

M. A. Whyte & M. Romano (2014)
First record of the pterosaur footprint Pteraichnus from the Saltwick
Formation (Aalenian) of the Cleveland Basin, Yorkshire, UK.
Proceedings of the Yorkshire Geological Society (advance online
publication) doi:10.1144/pygs2014-338
http://pygs.lyellcollection.org/content/early/2014/04/22/pygs2014-338.abstract?sid=47ef02ea-e8d4-4950-855d-54fb9c74b992

Prints belonging to Pteraichnus are recorded and described from the
Saltwick Formation (Middle Jurassic, Aalenian Stage) at Hayburn Wyke
on the Cleveland Coast of Yorkshire, England. This is the first record
of Pteraichnus from the region and from the British Isles, and is an
important addition to its diverse vertebrate ichnofauna. It is also
only the second record of pterosaur footprints from the British Isles
and is the oldest known occurrence of Pteraichnus. Significantly, it
suggests that the pterodactyloid pterosaurs evolved earlier than has
previously been supposed.

==

Matthew Parfitt, Zerina Johanson, Sam Giles & Matt Friedman (2014)
A large, anatomically primitive tristichopterid (Sarcopterygii:
Tetrapodomorpha) from the Late Devonian (Frasnian) Alves Beds, Upper
Old Red Sandstone, Moray, Scotland.
Scottish Journal of Geology (advance online publication)
doi:10.1144/sjg2013-013
http://sjg.lyellcollection.org/content/early/2014/04/09/sjg2013-013.abstract


A nearly complete mandible of a large tetrapodomorph sarcopterygian
from the Frasnian Alves Beds is studied with the aid of computed
tomography. The absence of cosmine, a small parasymphysial dental
plate bearing dentition that is discontinuous with that of the
coronoids, and the presence of an elongated posterior coronoid that
bears two fang pairs restrict placement of the tetrapodomorph from the
Alves Beds to Tristichopteridae, and suggest that is a member of the
clade that is sister to the anatomically primitive Givetian genus
Tristichopterus. Taxa from this segment of tristichopterid phylogeny
include the Givetian–Frasnian Eusthenopteron and Frasnian Jarvikina,
but the tristichopterid from the Alves Beds is distinguished from both
by the presence of an organized row of well-developed teeth on the
posterior coronoid. This character has been proposed as a synapomorphy
of taxa crownward of Trischopteridae, but is widely distributed among
tetrapodomorph fishes. Our reinterpretation of lower jaw material of
Tinirau clackae suggests this species is a member of the
Tristichopteridae rather than the ‘Elpistostegalia’, and likely
includes material assigned to a second species and genus of
tetrapodomorph from the Red Hill site, Bruehnopteron murphyi. Proposal
of a formal taxonomic name for the tristichopterid from the Alves Beds
is withheld pending the discovery or analysis of further material from
these deposits.

==
Many thanks to Vahe Demirjian for bringing this older ref to my attention.

Two older taxa not mentioned on the DML:

aetosaur Apachesuchus Spielmann &  Lucas, 2012
cynodont Redondagnathus Spielmann &  Lucas, 2012

Justin A. Spielmann &  Spencer G. Lucas (2012)
Tetrapod fauna of the Upper Triassic Redonda Formation, east-central
New Mexico; the characteristic assemblage of the Apachean
land-vertebrate faunachron.
Bulletin - New Mexico Museum of Natural History and Science 55: 1-119
http://econtent.unm.edu/utils/getfile/collection/bulletins/id/1854/filename/3370.pdf

In east-central New Mexico (principally Quay and Guadalupe counties),
the Upper Triassic Redonda Formation is the stratigraphically highest
unit in the Chinle Group. It unconformably(?) overlies the Upper
Triassic Bull Canyon Formation and is unconformably overlain by strata
that range in age from Middle Jurassic to Pleistocene. As much as 92 m
thick, the Redonda Formation has been divided into five members (in
ascending order): Quay, San Jon Creek, Duke Ranch, Wallace Ranch and
Montoya Point (laterally equivalent to the Duke Ranch and Wallace
Ranch members). Redonda deposition took place in an alluvial system
that comprised a mosaic of lakes, lake margins, fluvial channels,
floodplains and stable interfluves. Fossil vertebrates occur
throughout the Redonda Formation, but are concentrated in the upper
Quay Member and the Duke Ranch Member. The tetrapod fossil assemblage
of the Redonda Formation, redescribed and revised here, consists of
the following taxa: the metoposaurid amphibian Apachesaurus gregorii
Hunt, 1993; the archosauriform Vancleavea campi Long and Murry, 1995;
the phytosaur Redondasaurus gregorii Hunt and Lucas, 1993a (= R.
bermani Hunt and Lucas, 1993a); the aetosaurs Apachesuchus heckerti
new genus and species, Redondasuchus reseri Hunt and Lucas, 1991 and
R. rineharti Spielmann, Hunt, Lucas and Heckert, 2006; the
sphenosuchids Sphenosuchidae indet. and Redondavenator quayensis
Nesbitt, Irmis, Lucas and Hunt, 2005; and the cynodont Redondagnathus
hunti, new genus and species. The tetrapod assemblage of the Redonda
Formation is characteristic of the Apachean land-vertebrate
faunachron, the time interval between the first appearance datum (FAD)
of the phytosaur Redondasaurus and the FAD of the crocodylomorph
Protosuchus. The Apachean can be recognized primarily by the
distribution of the phytosaur Redondasaurus, which is found in New
Mexico and Utah, with closely allied taxa known from Germany.
Correlation of the Apachean by vertebrate and conchostracan
biostratigraphy indicates it is of late Norian-Rhaetian age.

==

Adrian Mitchell Currie (2014)
Venomous Dinosaurs and Rear-Fanged Snakes: Homology and Homoplasy Characterized.
Erkenntnis 79(3): 701-727
DOI: 10.1007/s10670-013-9533-5
http://link.springer.com/article/10.1007/s10670-013-9533-5

I develop an account of homology and homoplasy drawing on their use in
biological inference and explanation. Biologists call on homology and
homoplasy to infer character states, support adaptationist
explanations, identify evolutionary novelties and hypothesize
phylogenetic relationships. In these contexts, the concepts must be
understood phylogenetically and kept separate: as they play divergent
roles, overlap between the two ought to be avoided. I use these
considerations to criticize an otherwise attractive view defended by
Gould, Hall, and Ramsey & Peterson. By this view, homology and
homoplasy can only be delineated qua some level of description, and
some homoplasies (parallelisms) are counted as homologous. I develop
an account which retains the first, but rejects the second, aspect of
that view. I then characterize parallelisms and convergences in terms
of their causal role. By the Strict Continuity account, homology and
homoplasy are defined phylogenetically and without overlaps, meeting
my restriction. Convergence and parallelisms are defined as two types
of homoplasy: convergent homoplasies are largely constrained by
external factors, while parallelisms are due to internal constraints.