gmane.science.dinosaurs.general

Ophthalmosaurian ichthyosaurs from Middle Jurassic of Argentina

Ben Creisler — 2013-05-17T15:15:58

From: Ben Creisler
bcreisler< at >gmail.com


A new online paper:


Marta S. Fernández and Marianella Talevi (2013)
Ophthalmosaurian (Ichthyosauria) records from the Aalenian–Bajocian of
Patagonia (Argentina): an overview.
Geological Magazine (advance online publication)
DOI: http://dx.doi.org/10.1017/S0016756813000058
http://128.232.233.5/action/displayAbstract?fromPage=online&aid=8920772&fulltextType=RA&fileId=S0016756813000058

The oldest ophthalmosaurian records worldwide have been recovered from
the Aalenian–Bajocian boundary of the Neuquén Basin in Central-West
Argentina (Mendoza and Neuquén provinces). Although scarce, they
document a poorly known period in the evolutionary history of
parvipelvian ichthyosaurs. In this contribution we present updated
information on these fossils, including a phylogenetic analysis, and a
redescription of ‘Stenopterygius grandis’ Cabrera, 1939. Patagonian
ichthyosaur occurrences indicate that during the Bajocian the Neuquén
Basin palaeogulf, on the southern margi

Largocephalosaurus (saurosphargid diapsid), new species from Triassic of China

Ben Creisler — 2013-05-17T15:14:23

From: Ben Creisler
bcreisler< at >gmail.com

A new online paper:


Chun Li, Da-Yong Jiang, Long Cheng, Xiao-Chun Wu and Olivier Rieppel (2013)
A new species of Largocephalosaurus (Diapsida: Saurosphargidae), with
implications for the morphological diversity and phylogeny of the
group.
Geological Magazine (advance online publication)
DOI: http://dx.doi.org/10.1017/S001675681300023X
http://128.232.233.5/action/displayAbstract?fromPage=online&aid=8920775&fulltextType=RA&fileId=S001675681300023X


Largocephalosaurus polycarpon Cheng et al. 2012 was erected after the
study of the skull and some parts of a skeleton and considered to be
an eosauropterygian. Here we describe a new species of the genus,
Largocephalosaurus qianensis, based on three specimens. The new
species provides many anatomical details which were described only
briefly or not at all in the type species, and clearly indicates that
Largocephalosaurus is a saurosphargid. It differs from the type
species mainly in having three premaxillary teeth, a very s

Re: Psittacosaurus juvenile herd behavior

Ben Creisler — 2013-05-16T15:55:42

From: Ben Creisler
bcreisler< at >gmail.com

Since this has not been commented on on the DML (it's mentioned on
some blogs), I would point out an important fact revealed in this
paper--the fossil nest of psittacosaurs with a cluster of juveniles
"guarded" by an adult is in fact a fake (shades of Archaeoraptor!).
This doctored fossil find is cited in various places as supposed
evidence of direct parental care in dinosaurs.


"Our close inspection of this cluster of 34 juveniles (DNHM D2156)
shows that the ‘adult’ skull has been added with glue, and so was not
part of the original specimen; there is no sedimentary connection to
the main slab below, and the skull rests loosely on top of that slab,
and is not in any way part of the sedimentary layer in which the
juveniles all occur, intertwined with each other. The evidence is that
the ‘adult’ skeleton just contains a few postcranial bones without any
articulation, and the skull position is much higher than the juvenile
bone-bed plane. The juveniles all seem

Aw: Re: Layperson question on endothermic dinosaurs

David Marjanovic — 2013-05-16T13:13:11

So far, so good...


Hang on a second. Here it's you who suddenly jumps to conclusions without evidence. We don't even know that much!


I can't remember specific papers, but there are people who have vehemently disagreed with this piece of textbook wisdom.

Re: Layperson question on endothermic dinosaurs

Kelly Clowers — 2013-05-15T22:54:10

NP. It gets everyone now and then.

Re: Layperson question on endothermic dinosaurs

Jura — 2013-05-15T22:25:48

Thanks. I didn't even catch that it was truncated. Stupid Yahoo mail.

Jason


lation, but insulation hinders
es not
i, M. 2009. Metabolic Correlates of

Re: Layperson question on endothermic dinosaurs

Kelly Clowers — 2013-05-15T22:11:06

Rescued from truncation:

On Wed, May 15, 2013 at 12:17 PM, Jura <pristichampsus< at >yahoo.com> wrote:

The truth is that we are no closer to knowing the thermophysiology of
dinosaur now then we were in the 70's and 80's when this whole thing
was called into question. The biggest problem with metabolism is that
differences between groups are  often a question of grade rather than
of structure. For instance the cell membranes of crocodiles and cows
are almost exactly the same. However cows incorporate more
polyunsaturated fatty acids in their cell membranes than crocs do.
This makes the cell membrane less efficient at retaining certain ions
which forces the protein pumps in the membranes to work harder to keep
proper ionic concentrations, ultimately giving cow cells higher
metabolic rates than croc cells. Wu et al. (2004) actually "turned" a
croc cell into a cow cell by changing the unsaturated fatty acid ratio
in the membranes. All of this is soft-tissue related and differs only
in  ratios. None of it fossilizes

Evolution of Theropod Tail into Stiff Aerodynamic Surface

Ben Creisler — 2013-05-15T21:34:59

From: Ben Creisler
bcreisler< at >gmail.com


New in PLoS ONE:

Michael Pittman, Stephen M. Gatesy, Paul Upchurch, Anjali Goswami &
John R. Hutchinson (2013)
Shake a Tail Feather: The Evolution of the Theropod Tail into a Stiff
Aerodynamic Surface.
PLoS ONE 8(5): e63115.
doi:10.1371/journal.pone.0063115
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0063115



Theropod dinosaurs show striking morphological and functional tail
variation; e.g., a long, robust, basal theropod tail used for
counterbalance, or a short, modern avian tail used as an aerodynamic
surface. We used a quantitative morphological and functional analysis
to reconstruct intervertebral joint stiffness in the tail along the
theropod lineage to extant birds. This provides new details of the
tail’s morphological transformation, and for the first time
quantitatively evaluates its biomechanical consequences. We observe
that both dorsoventral and lateral joint stiffness decreased along the
non-avian theropod lineage (between nodes

Mapusaurus (Theropoda) bonebed pathology survey

Ben Creisler — 2013-05-15T21:31:07

From: Ben Creisler
bcreisler< at >gmail.com

New in PLoS ONE:

Phil R. Bell & Rodolfo A. Coria (2013)
Palaeopathological Survey of a Population of Mapusaurus (Theropoda:
Carcharodontosauridae) from the Late Cretaceous Huincul Formation,
Argentina.
PLoS ONE 8(5): e63409.
doi:10.1371/journal.pone.0063409
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0063409



Paleoepidemiology (the study of disease and trauma in prehistoric
populations) provides insight into the distribution of disease and can
have implications for interpreting behavior in extinct organisms. A
monospecific bonebed of the giant carcharodontosaurid Mapusaurus
(minimum number of individuals = 9) from the Cañadón del Gato site,
Neuquén Province, Argentina (Cenomanian) provides a rare opportunity
to investigate disease within a single population of this important
apex predator. Visual inspection of 176 skeletal elements belonging to
a minimum of nine individuals yielded a small number of abnormalities
on a cervical vertebra, two

Aniksosaurus (Theropoda) bonebed found in Upper Cretaceous Bajo Barreal Formation, Argentina

Ben Creisler — 2013-05-15T21:26:07

From: Ben Creisler
bcreisler< at >gmail.com


New in open-access PLoS ONE:

Lucio M. Ibiricu, Rubén D. Martínez,  Gabriel A. Casal & Ignacio A. Cerda (2013)
The Behavioral Implications of a Multi-Individual Bonebed of a Small
Theropod Dinosaur.
PLoS ONE 8(5): e64253
doi:10.1371/journal.pone.0064253
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0064253


Background

Central Patagonia, Argentina, preserves an abundant and rich fossil
record. Among vertebrate fossils from the Upper Cretaceous Bajo
Barreal Formation of Patagonia, five individuals of the small,
non-avian theropod dinosaur Aniksosaurus darwini were recovered. Group
behavior is an important aspect of dinosaur paleoecology, but it is
not well-documented and is poorly understood among non-avian
Theropoda.

Methods/Principal Findings

The taphonomic association of individuals from the Bajo Barreal
Formation and aspects of their bone histology suggest gregarious
behavior for Aniksosaurus, during at least a portion of the life
history of thi

Aw: RE: Layperson question on endothermic dinosaurs

David Marjanovic — 2013-05-15T21:14:45

Two things:

1) You, or your sbelchequer, wrote "monospecific boneheads". :-D :-D :-D

2) Crocodiles have "leaky" mitochondria!?! I'd say that clinches it! Reference, please!

Re: Layperson question on endothermic dinosaurs

Jura — 2013-05-15T19:17:48

The truth is that we are no closer to knowing the thermophysiology of dinosaur now then we were in the 70's and 80's when this whole thing was called into question. The biggest problem with metabolism is that differences between groups are often a question of grade rather than of structure. For instance the cell membranes of crocodiles and cows are almost exactly the same. However cows incorporate more polyunsaturated fatty acids in their cell membranes than crocs do. This makes the cell membrane less efficient at retaining certain ions which forces the protein pumps in the membranes to work harder to keep proper ionic concentrations, ultimately giving cow cells higher metabolic rates than croc cells. Wu et al. (2004) actually "turned" a croc cell into a cow cell by changing the unsaturated fatty acid ratio in the membranes. All of this is soft-tissue related and differs only in ratios. None of it fossilizes which means we have no real way of saying
 definitively anything about metabolic rate.

So we typical

Re: Layperson question on endothermic dinosaurs

Kelly Clowers — 2013-05-15T19:13:55

Thanks a lot, and thanks to everyone for the replies so far!

Kelly

RE: Layperson question on endothermic dinosaurs

Thomas R. Holtz, Jr. — 2013-05-15T17:43:26

Here are some lecture notes: http://www.geol.umd.edu/~tholtz/G204/lectures/204endo.html

Thomas R. Holtz, Jr.
Email: tholtz< at >umd.eduPhone: 301-405-4084
Office: Centreville 1216
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661

Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
Fax: 301-314-9843

Mailing Address:Thomas R. Holtz, Jr.
Department of Geology
Building 237, Room 1117
University of Maryland
College Park, MD 20742 USA

RE: Layperson question on endothermic dinosaurs

Allan Edels — 2013-05-15T17:33:11

[Speaking as another layperson:] 

The likelihood is that the large sauropods and the larger of the ornithischians would feel warm to the touch.   The bigger problem for these creatures would need help reducing the heat retained by the large mass, as well as that generated by the muscles as they moved.

(Long necks and tails might have facilitated some thermal reduction, as might the plates on stegosaurs, etc).

I've often wondered what a good Finite Element Analysis (FEA) of the movement of sauropods might shine on their heat production.

Allan Edels

Re: Layperson question on endothermic dinosaurs

Vivian Allen — 2013-05-15T17:05:57

Theropods, yeah. You've got several lines of evidence that make that
one pretty solid. Off the top of my head:

Feathers. I know feathers have other functions (display,
water-proofing, flying eventually) but I'm going to go out on a limb
and say one of the main things feathers do is insulate the body. Why
would you need to insulate yourself if you were not warm-blooded?

Extensive, bird-like lungs.  Most theropods had very large, complex
breathing structures similar to those seen in birds. In birds, these
lung complexes are very efficient at extracting a lot of oxygen from
the air (http://en.wikipedia.org/wiki/Bird_anatomy#Respiratory_system),
and you need a lot of oxygen to power a high metabolism. So again, why
have these complex lung structures unless you need a lot of oxygen?

Relationship with birds. Less concrete, but the fact is that birds are
living theropod dinosaurs, and they are endothermic. You may argue
that this is just because they fly, but many species of birds have
become more-or-less terres

Layperson question on endothermic dinosaurs

Kelly Clowers — 2013-05-15T16:34:01

Hi, I am hoping that I could get sense of  what the consensus, if any,
is on endothemry. I try to stay up to date and knowledgeable on all
things dino-related, but I just want to be clear on this to help
settle a discussion on the Ars Technica forums.

I believe that it pretty solidly accepted for therapods, but maybe
somewhat less so for the rest? Or am I all wrong?

Thanks very much,

Kelly Clowers

Psittacosaurus juvenile herd behavior

Ben Creisler — 2013-05-15T15:31:48

From: Ben Creisler
bcreisler< at >gmail.com


A new online open-access paper:


Qi Zhao, Michael J. Benton, Xing Xu, and Martin J. Sander (2013)
Juvenile-only clusters and behaviour of the Early Cretaceous dinosaur
Psittacosaurus.
Acta Palaeontologica Polonica (in press)
doi: http://dx.doi.org/10.4202/app.2012.0128
http://app.pan.pl/article/item/app20120128.html


It has hitherto been hard to prove that any association of juvenile
dinosaurs represents original behaviour rather than sedimentary
accumulation, and it has been hard also to determine the ages of such
juveniles. A previously described specimen, which consists of an
‘adult’ Psittacosaurus with 34 fully articulated juveniles, turns out
to be a composite: the ‘adult’ skull has been added, and in any case
it is below breeding age. Other juvenile-only clusters have been
reported, but the best examples that likely reflect behaviour rather
than sedimentary accumulation are specimens from the Early Cretaceous
Lujiatun beds in NE China, which were entom

Dinosaur parental incubation behavior and clutch size

Ben Creisler — 2013-05-15T15:10:04

From: Ben Creisler
bcreisler< at >gmail.com


A new paper:


Geoffrey F. Birchard, Marcello Ruta, and D. Charles Deeming (2013)
Evolution of parental incubation behaviour in dinosaurs cannot be
inferred from clutch mass in birds.
Biology Letters 9(4): 20130036;
doi:10.1098/rsbl.2013.0036
http://rsbl.royalsocietypublishing.org/content/9/4/20130036.abstract

A recent study proposed that incubation behaviour (i.e. type of
parental care) in theropod dinosaurs can be inferred from an
allometric analysis of clutch volume in extant birds. However, the
study in question failed to account for factors known to affect egg
and clutch size in living bird species. A new scaling analysis of
avian clutch mass demonstrates that type of parental care cannot be
distinguished by conventional allometry because of the confounding
effects of phylogeny and hatchling maturity. Precociality of young but
not paternal care in the theropod ancestors of birds is consistent
with the available data.

RE: Malawania, new "old-fashioned" ichthyosaur from Iraq

Ben Creisler — 2013-05-15T15:08:00

From: Ben Creisler
bcreisler< at >gmail.com


The paper is now out:

Valentin Fischer, Robert M. Appleby, Darren Naish, Jeff Liston, James
B. Riding, Stephen Brindley, and Pascal Godefroit (2013)
A basal thunnosaurian from Iraq reveals disparate phylogenetic origins
for Cretaceous ichthyosaurs.
Biology Letters 9(4):  20130021
doi:10.1098/rsbl.2013.0021
http://rsbl.royalsocietypublishing.org/content/9/4/20130021.abstract

Cretaceous ichthyosaurs have typically been considered a small,
homogeneous assemblage sharing a common Late Jurassic ancestor. Their
low diversity and disparity have been interpreted as indicative of a
decline leading to their Cenomanian extinction. We describe the first
post-Triassic ichthyosaur from the Middle East, Malawania anachronus
gen. et sp. nov. from the Early Cretaceous of Iraq, and re-evaluate
the evolutionary history of parvipelvian ichthyosaurs via phylogenetic
and cladogenesis rate analyses. Malawania represents a basal grade in
thunnosaurian evolution that arose during a major La

RE: Diegocanis, new eucynodont from Triassic Ischigualasto Formation, Argentina (free pdf)

Ben Creisler — 2013-05-15T03:03:15

From: Ben Creisler
bcreisler< at >gmail.com


My bad. The page numbers were wrong on the citation. Here's the
corrected reference:


Ricardo N. Martínez, Eliana Fernandez & Oscar A. Alcober (2013)
A new non-mammaliaform eucynodont from the Carnian-Norian
Ischigualasto Formation, Northwestern Argentina.
REVISTA BRASILEIRA DE PALEONTOLOGIA 16 (1): 61-76
doi:10.4072/rbp.2013.1.05
http://www.sbpbrasil.org/revista/edicoes/16_1/05_Martinez_et_al.pdf


The record of non-mammaliaformes eucynodonts from the Carnian-Norian
Ischigualasto Formation is diverse and abundant, including a medium to
large size herbivore and small carnivores. Here is described a new
small eucynodont from the Ischigualasto Formation, on the basis of a
partial skull. The new taxon is characterized by palatal process of
the premaxilla extending posterior to the level of the fi rst
postcanine; deep and large maxillary laterodorsal fossa that opens at
the level of the root of the upper canine; and postorbital bar
diverging posterolaterally at very low