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RE: Small theropod dinosaurs from Morrison Formation of Como Bluff, Wyoming (free pdf)

This paper and Dalman's other one in this volume naming a new Allosaurus 
species are... what's the word?  Terrible.  Admittedly, I've just skimmed them 
so far, but let's look at his new supposed ceratosaurid Fosterovenator.  The 
holotype is a partial tibia with fused astragalus, and the paratype is a 
supposed fibula "of a much larger individual".  So how can it be referred to 
Fosterovenator if it can't be compared to it?  Maybe they both have 
ceratosaurid features, you say?  Dalman says the tibia "clearly belongs to a 
basal tetanuran theropod that differs from all other known taxa from
the Morrison Formation by a strongly inclined anterior articular surface and by 
the “C”-shaped incisura tibialis."  Wait, what?  An impossible ceratosaurid 
tetanurine?  Later we read "Fosterovenator churei (YPM VP 058267) is identified 
as a ceratosaurid theropod, which based on its overall morphology is more 
closely related to Elaphrosaurus than to Ceratosaurus."  So... Elaphrosaurus is 
a ceratosaurid too in Dalman's view?  And just after that- "Therefore, based on 
this evidence both the Fosterovenator and the Garden Park “Elaphrosaurus” 
(Chure, 2001) most likely represent the first occurrence of basal Late Jurassic 
abelisauroids in the Northern Hemisphere."  Ohhh, so it's a tetanurine, 
abelisauroid ceratosaurid?  Triply impossible.  Note nowhere in the paper is 
the attempt even made to identify features that are most similar to 
Ceratosaurus or Elaphrosaurus.  Ironically, the tibia IS clearly tetanurine 
because its fibular crest is widely separated from the lateral condyle, n
 ot that Dalman mentions this character at all.  So this is no ceratosaur.  The 
'fibula' on the other hand, is pretty certainly not a theropod fibula.  There's 
almost no distal taper to the shaft, the distal end is 84% as wide 
anteroposteriorly as the proximal end, etc..  The distal end has the triangular 
outline of a tetanurine tibia, so if this belongs to a theropod, my guess is 
it's a tibia with a crushed and/or broken proximal end.  And it's not just the 
y.  Behold this wonderous section of text-

"In medial view the YPM VP 058267D tibia closely resembles the tibia of YPM VP 
058267A, which is a small bone and most likely belongs to a juvenile 
individual. Therefore, some of the morphological features may represent 
ontogenetic variation. In medial view, the (YPM VP 058267A) tibia closely 
resembles the tibia of some basal tetanuran theropods such as Neovenator and 
Sinraptor, but also those of small abelisauroid theropods. YPM VP058267A is a 
small bone and most likely belongs to a juvenile individual. Therefore, some of 
the morphological features may represent ontogenetic variation."

Who edited this?  Also note D is supposed to be the fibula, though the tibial 
pieces are also labeled D in the figure, although the text clearly says the 
proximal tibia is A.  The distal tibia with attached astragalus is 
alternatively identified as B or C, so who knows which is right for that one.

As for Allosaurus lucasi, note this is the specimen from Dalman et al.'s (2012) 
SVP abstract.  It's based on fragments that are photographed in Malkani-style- 
low resolution with no indication of what are broken surfaces.  In 2012, it was 
reported to have four premaxillary teeth, but is here correctly described as 
having five.  Though claimed in both places to have an unusually short 
premaxilla, it matches the A. fragilis premaxilla drawn next to it almost 
exactly in length vs. height.  The masterful editing is obvious two ways in 
this figure alone- A. fragilis' picture is credited to Madsen 1993 instead of 
1976, a mistake that is repeated everywhere including the bibliography; and 
what's supposed to be Neovenator's premaxilla clearly is not, with a short body 
and three teeth.  As with Fosterovenator, Dalman refers another specimen to A. 
lucasi, a smaller dentary fragment and supposed splenial fragment, that aren't 
said to share any unique characters with the dentary fragment
  of the holotype.  The SVP abstract says "All the cranial elements, including 
the braincase, left premaxilla, maxilla, 
t digital 3D reconstructions could be done, allowing morphological description 
and comparisons", but there's no evidence of that here.  In short, A. lucasi is 
just a fragmentary A. fragilis.

Seriously, whoever edited these (the acknowledgements suggest Spencer Lucas) 
was asleep at the wheel or just didn't care.  I'd be very interested to know 
how the claimed peer review by Lucas, Hunt, Foster and (the one who wisely 
chose to remain) Anonymous went down.

References- Dalman, Paulina-Carabajal and Currie, 2012. A new large-bodied 
theropod dinosaur from the Upper Morrison Formation (Late Jurassic, Tithonian) 
of Colorado. Journal of Vertebrate Paleontology. Program and Abstracts 2012, 84.

Dalman, 2014a. Osteology of a large allosauroid theropod from the Upper 
Jurassic (Tithonian) Morrison Formation of Colorado, USA. Volumina Jurassica. 
12(2), 159-179.

Dalman, 2014b. New data on small theropod dinosaurs from the Upper Jurassic 
Morrison Formation of Como Bluff, Wyoming, USA. Volumina Jurassica. 12(2), 

Mickey Mortimer

> Date: Mon, 15 Dec 2014 12:51:39 -0800
> From: bcreisler@gmail.com
> To: dinosaur@usc.edu
> Subject: Small theropod dinosaurs from Morrison Formation of Como Bluff, 
> Wyoming (free pdf)
> Ben Creisler
> bcreisler@gmail.com
> A new paper in open access:
> Sebastian G. Dalman (2014)
> New data on small theropod dinosaurs from the Upper Jurassic Morrison
> Formation of Como Bluff, Wyoming, USA
> Volumina Jurassica 12 (2): 181-196
> DOI : 10.5604/17313708 .1130142
> https://www.voluminajurassica.org/volumina/article/view/171/151
> In 1879, Othniel C. Marsh and Arthur Lakes collected in the Upper
> Jurassic Morrison Formation Quarry 12 at Como Bluff, Wyoming, USA,
> several isolated axial and appendicular skeletal elements of small
> theropod dinosaurs. Since the discovery the specimens remained
> unnoticed for over a century. The skeletal remains of small theropods
> are rare at Como Bluff and throughout the Morrison Formation. Their
> bones are d

> the bones of large-bodied theropods. The bones of small theropods
> described here were found mixed with isolated crocodile teeth and
> turtle shells. Comparison of the skeletal materials with other known
> theropods from the Morrison Formation reveals that some of the bones
> belong to a very small juvenile Allosaurus fragilis and Torvosaurus
> tanneri and also to a new ceratosaur taxon, here named Fosterovenator
> churei, whereas the other bones represent previously unidentified
> juvenile taxa of basal tetanuran and coelurid theropods. The discovery
> and description of these fossil materials is significant because they
> provide important information about the Upper Jurassic terrestrial
> fauna of Quarry 12, Como Bluff, Wyoming. The presence of previously
> unidentified theropod taxa in the Morrison Formation indicates that
> the diversity of basal tetanuran and coelurid theropods may have been
> much greater than previously expected. Although the fossil material
> here described is largely fragmentary, it is tenable that theropods of
> different clades co-existed in the same ecosystems at the same time
> and most likely competed for the same food sources.
> ===