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Non-dino papers in new JVP: mammal limbs, marine snakes,lepospondyls

From: Ben Creisler

A number of papers in the new JVP that may be of interest:

Thomas Martin (2013)
Mammalian postcranial bones from the Late Jurassic of Portugal and
their implications for forelimb evolution.
Journal of Vertebrate Paleontology 33 (6):  1432-1441
DOI: 10.1080/02724634.2013.771780

Isolated bones of forelimb and pelvic girdle (two humeri, five ulnae,
and an ilium) recovered from the Late Jurassic (Kimmeridgian)
Guimarota coal mine in western central Portugal are attributed to the
docodont Haldanodon exspectatus, dryolestoids, and a ?paulchoffatiid
multituberculate. The larger of the two humeri is assigned to the
dryolestid Dryolestes leiriensis based on size and shape. It clearly
exhibits an incipient trochlea at the distal joint, suggesting that
this derived character was well established among Late Jurassic
dryolestidans, including Henkelotherium. Plesiomorphic characters are
the prominent spherical radial condyle and the weakly developed ulnar
condyle. An incipient medial keel is present in distal aspect of the
humerus trochlea. The shallow olecranon fossa of the humerus
corresponds to the small anconeal process of the radius. The smaller
humerus with damaged distal joint is 50% smaller and cannot be
assigned to a specific dryolestoid taxon. It is in the size range of
the smaller Guimarota dryolestoids Krebsotherium, Drescheratherium,
and Henkelotherium. One ulna differs from the dryolestoid ulnar shape
by the nearly semicircular articular surface for the ulnar condyle of
the humerus, the asymmetric olecranon with medial overhang, as well as
the prominent anconeal process and is tentatively attributed to a
paulchoffatiid multituberculate.

Alessandro Palci, Michael W. Caldwell & Randall L. Nydam (2013)
Reevaluation of the anatomy of the Cenomanian (Upper Cretaceous)
hind-limbed marine fossil snakes Pachyrhachis, Haasiophis, and
Journal of Vertebrate Paleontology 33 (6):  1328-1342
DOI: 10.1080/02724634.2013.779880

New anatomical observations and reinterpretations of previously
identified structures have resulted in new taxonomic diagnoses for the
fossil hind-limbed marine snakes Pachyrhachis problematicus,
Eupodophis descouensi, and Haasiophis terrasanctus. Among the most
important conclusions of our study are the following: Haasiophis and
Eupodophis show no evidence of possessing a laterosphenoid;
Pachyrhachis and Eupodophis do retain a jugal; Haasiophis, like
Eupodophis, has chevron bones in the caudal region; Haasiophis has a
large number of unfused intercentra along the anterior portion of the
precloacal column; the dentary of Pachyrhachis has numerous mental
foramina (at least four); Pachyrhachis has at least one sacral
vertebra with unfused sacral ribs. To test the effect of our new
observations on the phylogenetic relationships of snakes, we ran three
phylogenetic analyses using alternative outgroups to polarize the
character transformations. The ingroup consisted of all well-preserved
fossil snakes from the Cretaceous, the madtsoiids, and taxa that are
representative of all major groups of extant snakes. The analyses
yielded a series of most parsimonious trees that placed Pachyrhachis,
Eupodophis, and Haasiophis either as a series of stem taxa at the base
of the radiation of snakes (two analysis), or as members of a clade of
fossil snakes that are the sister group of all living alethinopidians
(one analysis).

Jennifer C. Olori (2013)
Morphometric analysis of skeletal growth in the lepospondyls
Microbrachis pelikani and Hyloplesion longicostatum (Tetrapoda,
Journal of Vertebrate Paleontology 33 (6):  1300-1320
DOI:  10.1080/02724634.2013.775141

Although morphological evidence alone appears insufficient to resolve
the problem of extant amphibian ancestry, comparison of developmental
processes and functional correlates of ontogenetic change may provide
a basis for evaluating relationships among extinct and extant
tetrapods. In the first allometric study of cranial and postcranial
growth in any lepospondyl, I investigate skeletal development in the
microsaurs Microbrachis pelikani and Hyloplesion longicostatum using
traditional measurement-based and geometric morphometric analyses.
Regression analyses against both skull and centrum lengths for M.
pelikani indicate positive allometric scaling of the interclavicle
plate length, pubis, and ilium, and negative scaling of the diameter
of the orbit. Preliminary data for H. longicostatum support negative
scaling of neural arch height and posterior centrum height. Results
from geometric morphometrics suggest slight widening of the cheek in
M. pelikani, rather than marked elongation. Overall, cranial and
postcranial growth in both microsaurs was primarily isometric and
comparison with allometric data from other Paleozoic taxa suggests
that isometric growth is an ancestral feature of development in early
tetrapods. All regression analyses for M. pelikani and H.
longicostatum had a constant linear slope, indicating that ontogenetic
trajectories were continuous, with gradual skeletal growth and no
shift in feeding or locomotor function during ontogeny. The lack of
morphological change suggests that these microsaurs did not undergo an
extant amphibian-like metamorphosis that included reorganization of
the skeleton. These data support the hypothesis that metamorphosis is
a derived mode of development present only in extant amphibians and
their closest relatives.