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Re: Papers in the new JVP

"The estimated mass for the
largest pterosaur known, Quetzalcoatlus northropi, exceeds the previous
highest estimates by more than 100%, and it is argued that this extremely
large pterosaur is better interpreted as a secondarily flightless form."

The first part seems quite plausible -- previous estimates were pretty low. The 
second does not - flightless species (of birds, anyway, which are our only 
examples since there are no flightless bats) tend to have reduced wings, which 
Q. emphatically does not.

For those without access to the paper, like myself, what is their estimated 
mass for Q. northropi?
----- Original Message -----
From: "Thomas R. Holtz, Jr." <tholtz@umd.edu>
To: "Dinosaur Mailing List" <dinosaur@usc.edu>
Sent: Friday, May 21, 2010 11:21:16 AM GMT -06:00 US/Canada Central
Subject: Papers in the new JVP (Resent in case the formatting of the last one 
didn't work)

The latest JVP is available to SVP members from the SVP site (start by
logging on at http://www.vertpaleo.org/source/security/member-
logon.cfm?section=unknown&activesection=home, then click on JVP in the left
column, then "click here" for access towards the center, then click on the
Taylor & Francis link). Here are some highlights:

Heckert, Andrew B. , Lucas, Spencer G. , Rinehart, Larry F. , Celeskey,
Matthew D. , Spielmann, Justin A. andHunt, Adrian P. 'Articulated skeletons
of the aetosaur Typothorax coccinarum Cope (Archosauria: Stagonolepididae)
from the Upper Triassic Bull Canyon Formation (Revueltian: early-mid
Norian), eastern New Mexico, USA', Journal of Vertebrate Paleontology,
30:3, 619 - 642  DOI: 10.1080/02724631003763524 

We report two nearly complete, articulated skeletons of the crurotarsan
archosaur Typothorax coccinarum from the Upper Triassic Bull Canyon
Formation of east-central New Mexico. These are the most complete,
articulated aetosaurs from North America and provide a wealth of new
anatomical and paleobiological data, including articulated presacral armor
that confirms the distinctiveness of T. coccinarum from the closely related
T. antiquum and from Redondasuchus. Cervical vertebrae are small, but the
corresponding reduction in armor is accomplished by a reduced number of
cervical osteoderms. The third row of osteoderms includes a thin, elongate,
lateral spike. The ventral armor consists of 10 thoracic columns and four
caudal columns of osteoderms. Spiked osteoderms near the cloacal vent are
the first spikes reported in aetosaurian ventral osteoderms. The forelimb
of T. coccinarum was very short, only â0.65 the length of the hind limb,
possesses some adaptations found in digging taxa, and was held in a
sprawling or 'semi-erect' position. In contrast the hind limb is much more
robust, 'pillar erect,' and functionally mesotarsal. The articulated pes,
including unguals, has, minimally, the phalangeal formula 2-3-3?-4?-3? with
relative digit lengths III > II > IV > I > V, digits I-IV equally as wide
as long and other characteristics of the footprint ichnogenus
Brachychirotherium, often attributed to an aetosaurian trackmaker. Both
specimens are â2.5 m long and the preserved armor and limb bones are as
large or larger than known Typothorax fossils, suggesting that this
approximates the upper size limit of T. coccinarum, and we calculate body
mass estimates of â100-104 kg for both specimens. 


Henderson, Donald M. 'Pterosaur body mass estimates from three-dimensional
mathematical slicing', Journal of Vertebrate Paleontology, 30:3, 768 - 785

Body masses for 14 species of pterosaur spanning four orders of magnitude
were estimated using three-dimensional, digital models. The modeled taxa
comprised seven paraphyletic 'rhamphorhynchoids': Anurognathus ammoni,
Dimorphodon macronyx, Eudimorphodon ranzii, Jeholopterus ningchengensis,
Preondactylus buffarinii, Rhamphorhynchus muensteri, and Sordes pilosus;
and seven pterodactyloids: Anhanguera santanae, Dsungaripterus weii,
Pteranodon longiceps, Pterodaustro guinazui, Pterodactylus sp.,
Quetzalcoatlus northropi, Tupuxuara longicristatus. The reliability of the
mass estimation methods were tested with equivalent models of six extant
species of bird with masses that spanned three orders of magnitude. The
close agreement between model bird mass estimates and those of the living
forms provides a level of confidence in the results obtained for the
extinct pterosaurs. The masses of the axial body regions (tail, trunk,
neck, head), limbs, and patagia of the pterosaurs were individually
estimated and distinct differences in relative body proportions were found
between species. Allometric relationships between body length and wingspan
and body mass were derived for 'rhamphorhynchoids' and pterodactyloids to
facilitate the estimation of body masses for other pterosaurs known from
incomplete material, and these relationships also highlight differences in
phyletic shape change between the two groups. The estimated mass for the
largest pterosaur known, Quetzalcoatlus northropi, exceeds the previous
highest estimates by more than 100%, and it is argued that this extremely
large pterosaur is better interpreted as a secondarily flightless form.

[Yes, reread that last sentence!!]


Lehman, Thomas M. 'Pachycephalosauridae from the San Carlos and Aguja
Formations (Upper Cretaceous) of West Texas, and Observations of the
frontoparietal dome', Journal of Vertebrate Paleontology, 30:3, 786 - 798

Several fragmentary frontoparietal domes from the San Carlos and Aguja
Formations (Campanian) of Brewster and Presidio Counties, Texas, are
referable to Pachycephalosauridae (Dinosauria: Ornithischia) and represent
a southern extension of the known range of these dinosaurs in North
America. Although the specimens are insufficient for confident generic
identification, the size, relative dome height and width, continuity of
frontal and parietal portions of the dome, and obliteration of sutures
between these bones suggest affinity with pachycephalosaurids as Stegoceras
and Gravitholus. More than one taxon is probably represented in the
collection. Sections taken from one of the domes reveal histological tissue
zonation comparable to that found in other pachycephalosaurids and growth
lines indicating that at least 5 years were required to attain adult size.
The bone tissue is well suited for strengthening the dome to resist
compressional loading, and is compatible with the hypothesis that these
animals engaged in head-butting behavior. 


Mcdonald, Andrew T. , Wolfe, Douglas G. andKirkland, James I. 'A new basal
hadrosauroid (Dinosauria: Ornithopoda) from the Turonian of New Mexico',
Journal of Vertebrate Paleontology, 30:3, 799 - 812

MSM P4166, a specimen from the Moreno Hill Formation (middle Turonian) of
New Mexico, is described as the holotype of a new genus and species of
hadrosauroid dinosaur. Jeyawati rugoculus, gen. et sp. nov., is diagnosed
by a rugose texture that covers the entire lateral surface of the
postorbital and the presence of a large neurovascular foramen at the base
of the jugal process of the postorbital, as well as a unique combination of
characters. A preliminary phylogenetic analysis reveals that Jeyawati is a
basal hadrosauroid more derived than Probactrosaurus, Eolambia, and
Protohadros, but more basal than Shuangmiaosaurus, Bactrosaurus, and
Telmatosaurus. Assessment of ontogenetic criteria indicates that MSM P4166
represents a subadult or adult individual. Even with the recognition of
Jeyawati, Late Cretaceous hadrosauroid biogeography remains somewhat
ambiguous because of the lack of material from the late Turonian-early
Santonian in western North America. 


Prieto-Marquez, Albert andSalinas, Guillermo C. 'A re-evaluation of
Secernosaurus koerneri and Kritosaurus australis (Dinosauria,
Hadrosauridae) from the Late Cretaceous of Argentina', Journal of
Vertebrate Paleontology, 30:3, 813 - 837

Hadrosaurids form the most diverse and derived clade of ornithopod
dinosaurs. Although well represented in Asia and North America, its
presence in South America is known only from rare and fragmentary remains
that are poorly documented and mostly unstudied. As a result, the impact of
these animals on the phylogenetics and biogeography of hadrosaurids as a
whole is poorly known. Here, we provide a revised and complete osteology of
the type specimens and hypodigms for the only two taxa known from South
America, Secernosaurus koerneri and Kritosaurus australis. Likewise, we
infer the phylogenetic position and historical biogeography of South
American hadrosaurids using a nearly complete taxonomic sampling of
hadrosaurid species. Parsimony methods were used to infer phylogenetic
relationships, whereas Fitch parsimony and Dispersal-Vicariance analyses
were implemented to reconstruct ancestral areas. Kritosaurus australis is
regarded as a junior synonym of Secernosaurus koerneri, based on a
combination of iliac and pubic characters unique to these two taxa.
Inclusion of S. koerneri within the genus Kritosaurus is not supported by
the phylogenetic analysis. S. koerneri is inferred to be a member of the
Kritosaurus-Gryposaurus clade within Saurolophinae, as the sister taxon to
the Argentinean unnamed hadrosaurid from Salitral Moreno. Another unnamed
hadrosaurid from Big Bend National Park, Texas, is positioned as the
closest outgroup to the South American clade. The results of this
biogeographical analysis supports the hypothesis that the Secernosaurus
clade originated in South America during the late Campanian after a
dispersal event (probably followed by vicariance) from southern North
America before the end of that geologic stage. 

[Another part of Albert's disseratation. On congrats to Mike Brett-Surman
for the support of his critter!]


Prieto-Marquez, Albert 'The braincase and skull roof of Gryposaurus
notabilis (Dinosauria, Hadrosauridae), with a taxonomic revision of the
genus', Journal of Vertebrate Paleontology, 30:3, 838 - 854

The facial and neurocranial anatomy of AMNH 5350, containing the most
complete braincase available for Gryposaurus, is described in detail. The
specimen, collected from Late Campanian outcrops of the Dinosaur Park
Formation of southern Canada, is referred to G. notabilis because of the
combination of a preorbital nasal protuberance positioned above the level
of the frontals, narrow U-shaped posterior margin of the narial fenestra,
dorsal margin of the infratemporal fenestra being wider than that of the
orbit, and posterodorsal margin of the squamosal located dorsal to the
skull roof. The flat nasal protuberance of AMNH 5350 differs from the
arcuate lateral profile displayed in other specimens of G. notabilis,
indicating that substantial intraspecific variation existed in this
feature. The taxonomy of Gryposaurus is revised in light of the newly
garnered anatomical data. Thus, G. incurvimanus is regarded as a junior
synonym of G. notabilis, composed of subadult specimens of the latter.
Characters thought to be diagnostic of G. incurvimanus are either present
in G. notabilis (e.g., slightly excavated ventral surface of the nasal
protuberance) or probably indicative of sub-adulthood (e.g., less developed
and more anteriorly positioned nasal protuberance correlated with smaller
skull size). A number of characters previously used to distinguish among
Gryposaurus sepecies are shown to be intraspecifically variable (e.g.,
curvature of the lateroventral margin of the maxilla or ventral deflection
of the dentary symphyseal process). 

[And yet ANOTHER part of Albert's disseration!]

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
Fax: 301-314-9661               

Faculty Director, Earth, Life & Time Program, College Park Scholars
Faculty Director, Science & Global Change Program, College Park Scholars
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