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Mesozoic mammal and Paleozoic synapsid stuff



From: Ben Creisler
bh480@scn.org

Some recent papers and a news story about synapsids, mammalian and
otherwise.

Anjali Goswami, Guntupalli V. R. Prasad, Paul Upchurch, Doug M. Boyer, Erik
R. Seiffert, Omkar Verma, Emmanuel Gheerbrant, and John J. Flynn (2011)
A radiation of arboreal basal eutherian mammals beginning in the Late
Cretaceous of India. 
Proceedings of the National Academy of Sciences (advance online publication)
DOI: 10.1073/pnas.1108723108 
http://www.pnas.org/content/early/2011/09/13/1108723108.abstract?sid=64ac6ac
c-8ea8-4dff-b02e-4206e2cbf84f


India's Late Cretaceous fossil mammals include the only undisputed
pre-Tertiary Gondwanan eutherians, such as Deccanolestes. Recent studies
have suggested a relationship between Deccanolestes and African and
European Paleocene adapisoriculids, which have been variably identified as
stem euarchontans, stem primates, lipotyphlan insectivores, or
afrosoricids. Support for a close relationship between Deccanolestes and
any of these placental mammal clades would be unique in representing a
confirmed Mesozoic record of a placental mammal. However, some
paleogeographic reconstructions place India at its peak isolation from all
other continents during the latest Cretaceous, complicating reconstructions
of the biogeographic history of the placental radiation. Recent fieldwork
in India has recovered dozens of better-preserved specimens of Cretaceous
eutherians, including several new species. Here, we incorporate these new
specimens into an extensive phylogenetic analysis that includes every clade
with a previously hypothesized relationship to Deccanolestes. Our results
support a robust relationship between Deccanolestes and Paleocene
adapisoriculids, but do not support a close affinity between these taxa and
any placental clade, demonstrating that Deccanolestes is not a Cretaceous
placental mammal and reinforcing the sizeable gap between molecular and
fossil divergence time estimates for the placental mammal radiation.
Instead, our expanded data push Adapisoriculidae, including Deccanolestes,
into a much more basal position than in earlier analyses, strengthening
hypotheses that scansoriality and arboreality were prevalent early in
eutherian evolution. This comprehensive phylogeny indicates that faunal
exchange occurred between India, Africa, and Europe in the Late
Cretaceous-Early Paleocene, and suggests a previously unrecognized ~30 to
45 Myr "ghost lineage" for these Gondwanan eutherians. 

***
P.M. Butler, D. Sigogneau-Russell,& P.C. Ensom (2011) 
Possible persistence of the morganucodontans in the Lower Cretaceous
Purbeck Limestone Group (Dorset, England).
Cretaceous Research (advance online publication)
doi:10.1016/j.cretres.2011.09.007
http://www.sciencedirect.com/science/article/pii/S0195667111001297

'Triconodonts' are relatively rare in the new Purbeck Limestone Group
mammal fauna, especially in comparison with the finds made in the
nineteenth century in the same beds. However, besides some remains of the
already known Triconodontidae, a new possible morganucodontan of uncertain
familial affinities, Purbeckodon batei gen. et sp. nov., has been
discovered, extending considerably the chronological range of the order
while constituting another testimony to the vitality and diversity of
Mesozoic mammals.

***
CLEMENS, W. A. (2011).
New morganucodontans from an Early Jurassic fissure filling in Wales
(United Kingdom). 
Palaeontology 54: 1139--1156. 
doi: 10.1111/j.1475-4983.2011.01094.x
http://onlinelibrary.wiley.com/doi/10.1111/j.1475-4983.2011.01094.x/abstract


Two new genera and species of morganucodontans, Bridetherium dorisae and
Paceyodon davidi, are recognized as members of the Morganucodon-sphenodont
fauna preserved in a fissure filling (Pant 4) exposed in Pant Quarry, Vale
of Glamorgan, southern Wales. Both taxa are based on isolated molariforms.
Mode of occlusion of upper and lower molariforms in B. dorisae differs from
the embrasure shearing pattern of Megazostrodon and the offset pattern
characteristic of Morganucodon. Lack of a clear correlation between
different patterns of occlusion and morphologies of their molariforms
supports the working hypothesis that a close correlation between function
and morphology of the molars characteristic of therian mammals, for
example, was not present in morganucodontans. P. davidi is based on an
isolated morganucodontan molariform that is significantly larger than any
yet discovered. Several isolated morganucodontan-like molariforms cannot be
referred to these taxa. The new Welsh morganucodontans added to records
from other sites indicate the group achieved considerable taxonomic
diversity and a near global distribution by the Early Jurassic.

***
Roger M.H. Smith & Jennifer Botha-Brink (2011) 
Morphology and composition of bone-bearing coprolites from the Late Permian
Beaufort Group, Karoo Basin, South Africa.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online
publication)
doi:10.1016/j.palaeo.2011.09.006
http://www.sciencedirect.com/science/article/pii/S0031018211004792
 

Bone-bearing coprolites are fossilized faeces of carnivores and as such
they provide important information about food webs and feeding strategies
of the ancient ecosystem. With this aim we examined the morphology and
composition of Late Permian bone-bearing coprolites from the Hoedemaker
Member of the Teekloof Formation (Lower Beaufort Group) of the southern
Karoo Basin, South Africa. Analysis of the size and shape of 150 specimens
collected from this member resulted in the recognition of 5 different
morphotypes. Each morphotype is matched to carnivorous taxa within the
Tropidostoma Assemblage Zone fauna which biostratigraphically defines the
Hoedemaker Member strata in this part of the basin. Morphotype 1 are long
cylinder-shaped non-segmented faeces, or possible cololites, rounded at
both ends and commonly contain complete small bones as well as bone
fragments and were most likely produced by the large gorgonopsians
Aelurognathus and Gorgonops torvus. Smaller, tubular Morphotype 2
coprolites are attributed to the smaller therocephalians and juvenile
gorgonopsians. Rare double-pointed Morphotype 3 are similar in size and
shape to scats of the modern wild cat and we attribute these to the
medium-sized gorgonopsians Cyonosaurus and Lycaenops or possibly juveniles
of the large gorgonopsian species. Morphotype 4 coprolites are
bullet-shaped and are interpreted as disaggregated portions of compound
faeces. They are the most common coprolite found in the Hoedemaker mudrocks
and are also attributed to small and medium-sized therocephalians and
gorgonopsians. Morphotype 5 are rare flattened disc-shaped coprolites that
contain abundant fish-scales and are linked to the temnospondyl,
Rhinesuchus africanus, the only known piscivore from the Tropidostoma
assemblage. Analyses of the microstructure of the bone inclusions within
morphotypes 1--4 revealed two distinct tissue types. Bone tissue type A
consists of highly vascularised, rapidly-forming bone interpreted as being
that of very young perinatal and/or early juvenile therapsids, probably
dicynodonts. Judging by the relative abundance of their body fossils, the
herbivorous dicynodonts were by far the most abundant tetrapods in the
Tropidostoma Assemblage Zone and it is probably that their young, both
embryonic and neonatal juveniles, were commonly preyed upon. Some of the
larger carnivores swallowed small prey whole, or with minimal mastication,
allowing complete limbs to pass through the digestive tract in
articulation. Inclusions of bone tissue type B, which consists of
poorly-vascularised, slow-growing bone, are interpreted to be the skeletal
remains of small parareptiles.

***

Andrew C. Rozefelds, Anne Warren, Allison Whitfield & Stuart Bull (2011)
New evidence of large Permo-Triassic dicynodonts (Synapsida) from Australia.
Journal of Vertebrate Paleontology 31(5):1158-1162.
DOI: 10.1080/02724634.2011.595858
http://www.tandfonline.com/doi/abs/10.1080/02724634.2011.595858
[no abstract but has full page preview]

****
This paper has been out for a time but apparently not mentioned yet on the
DML:

Christian F. Kammerer (2011)
Systematics of the Anteosauria (Therapsida: Dinocephalia).
Journal of Systematic Palaeontology 9(2):261-304
DOI:10.1080/14772019.2010.492645
http://www.tandfonline.com/doi/abs/10.1080/14772019.2010.492645

Anteosaurs (Therapsida: Dinocephalia: Anteosauria) were the dominant
terrestrial predators during the late Middle Permian period and are known
from southern Africa, the former USSR, China and Brazil. This paper
presents a critical taxonomic review of all known anteosaur taxa and a
reevaluation of anteosaurian interrelationships. The following anteosaur
species are considered to be valid: Anteosaurus magnificus, Archaeosyodon
praeventor, Australosyodon nyaphuli, Microsyodon orlovi, Notosyodon gusevi,
Sinophoneus yumenensis, Syodon biarmicum, Titanophoneus adamanteus and T.
potens. Syodon efremovi is considered a junior synonym of S. biarmicum,
Stenocybus acidentatus to represent juvenile material of Sinophoneus
yumenensis, Doliosauriscus yanshinovi a junior synonym of Titanophoneus
potens, and Paranteosaurus primus a junior synonym of Anteosaurus
magnificus. Admetophoneus kargalensis, Archaeosuchus cairncrossi, Brithopus
bashkyricus, B. ponderus, B. priscus, Eccasaurus priscus, Lamiasaurus
newtoni and Orthopus primaevus are regarded as nomina dubia.
?Titanophoneus? rugosus is tentatively considered the first representative
of the genus Anteosaurus in Russia. Phylogenetic analysis of anteosaurs
recovers a monophyletic Anteosauridae containing two major clades,
Syodontinae (containing Australosyodon, Notosyodon and Syodon) and
Anteosaurinae (containing Anteosaurus, Sinophoneus and Titanophoneus). The
Russian taxa Archaeosyodon and Microsyodon represent the most basal
anteosaurs. Anteosaurian skulls share many features in common with those of
large-bodied predatory taxa such as tyrannosaurid dinosaurs, and
anteosaurines in particular exhibit characters associated with handling
large prey items and possibly bone-crushing.


***
This news item was in Portuguese, translated here with a little help from
Google Translate with tweaking. I replaced the misused term "dinosaurs" in
a few places---Paleozoic parareptiles and synapsids usually get short
shrift because they are NOT dinosaurs. Maybe this Russian news item will
show up in an English language release at some point.

http://www.diariodarussia.com.br/fatos/noticias/2011/09/20/russia-regiao-de-
kirov-reconhece-importancia-economica-dos-dinossauros/

Kirov region of Russia recognizes economic importance of [prehistoric
reptiles].
A monument in recognition of the importance of the [ancient reptiles] that
went extinct 250 million years ago will be inaugurated in 2012 in a train
station in the city of Kotelnitch, in the Kirov region, considered the site
of greatest concentration of fossils of prehistoric reptiles of the
Paleozoic Era.

The passenger trains will be greeted with bronze sculptures of Pareiasaurus
and gorgonopsian species, as a kind of thank you note from residents to
visitors. The inhabitants of Kotelnitch want to show the primarily economic
importance that  [prehistoric reptiles] have for the region, because they
attract more and more tourists.




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