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Ichthyosauria review and other new papers
From: Ben Creisler
No dinosaur stuff as such but in case these new Mesozoic
vertebrate papers have not been mentioned yet:
The new issue of Palaeodiversity with a supplement is
Note that the pdfs are free!
A number of papers might be of interest to some DML
MICHAEL W. MAISCH, 2010.
Phylogeny, systematics, and origin of the Ichthyosauria --
the state of the art.
Palaeodiversity 3: 151?214 (December 2010)
A historical overview and a synopsis of the current
knowledge on the phylogeny, systematics, and phylogenetic
position of the Ichthyosauria are presented. All known
ichthyosaur taxa are listed, new taxa are discussed and
diagnosed. The following new taxa are erected:
Thaisauridae n. fam., Wimaniidae n. fam.,
Barracudasauroides n. gen. with Mixosaurus panxianensis
JIANG et al., 2006 as type species, as well as the
species Omphalosaurus merriami n. sp. Merriamosaurus
MAISCH & MATZKE, 2003 is a junior synonym of Pessopteryx
WIMAN, 1910. ?Ichthyosaurus? acutirostris OWEN, 1840
probably represents a genus of its own.
Based on this summary of our current understanding of the
group as a whole, ichthyosaurs are included in two of the
largest and more widely used phylogenetic analyses of the
Amniota. Character codings and their justiﬁcations are
discussed. No clear signal on the phylogenetic position
of the Ichthyosauria results from these analyses.
Instead, they are in one case nested within the Diapsida,
but with the anapsid Mesosauria as their sister group. In
the other case they are nested within Parareptilia, with
Procolophonia (Testudines, Pareiasauria) as sister group.
In contrast to previous assumptions, the inclusion of
ichthyosaurs in these large-scale analyses always changes
the original topology of the resulting cladograms so that
turtles and pareiasaurs become sister groups. This
underlines the importance of the taxon Ichthyosauria for
any future large-scale phylogenetic analyses of
amniotes.At the present state of knowledege, a deﬁ nite
decision on the origin and phylogenetic position of
ichthyosaurs is still impossible, but descent from
primarily anapsid ancestors and an origin from among the
Parareptilia can not be excluded as an alternative to a
diapsid origin of the group.
Keywords: Ichthyosauria, systematics, taxonomy,
phylogeny, origin, phylogenetic analysis, Amniota.
STERLING J. NESBITT & DAVID W. E. HONE, 2010.
An external mandibular fenestra and other archosauriform
character states in basal pterosaurs.
Palaeodiversity 3: 225?233 (December 2010).
Pterosauria, a successful clade of extinct ﬂying
vertebrates, possesses a radical body plan that offers
few clues about their origin and closest relatives.
Whereas most researchers hypothesize an origin within
Archosauria as the sister-group to Dinosauromorpha,
others favor a position among non-archosauriform
archosauromorphs. Here we present evidence that supports
a placement within Archosauriformes: the presence of an
external mandibular fenestra in two basal pterosaur taxa,
Dimorphodon macronyx and a specimen referred to
Eudimorphodon cf. ranzii (= ?Seefeld Eudimorphodon?; BSP
1994 I 51). Furthermore, the arrangement of the
mandibular bones surrounding the mandibular fenestra and
the presence of a posterior process of the dentary that
laterally overlaps the angular inthe mandible of
Dimorphodon and BSP 1994 I 51 are identical to those of
Erythrosuchus, Euparkeria, and Archosauria. When mapped
on a cladogram, presence or absence of an external
mandibular fenestra in basal pterosaurs possibly
indicates that the feature is primitive for Pterosauria
but later lost. The presence of an external mandibular
fenestra, along with morphological evidence elsewhere in
the body of pterosaurs (serrated teeth, antorbital fossa
present, fourth trochanter on the femur present),
supports a placement of Pterosauria within
Archosauriformes and is consistent with a position within
K e y w o r d s : Pterosauria, archosaur, dinosauromorph,
JULIEN KIMMIG & GERNOT ARP, 2010.
Phytosaur remains from the Norian Arnstadt Formation
(Leine Valley, Germany), with reference to European
Palaeodiversity 3: 215?224 (December 2010)
Most inferences on phytosaur ecology are based on
comparisons with extant crocodilians, in particular with
reference to similarities in their skull morphology. In
addition, the sedimentary environment of their place of
embedding provides information on their life habitat and
the potential lifestyle of these animals. Here we report
on newly discovered phytosaur remains from the Norian
Arnstadt Formation, which support the interpretation that
the European phytosaur genera Mystriosuchus and
Nicrosaurus had different ecological preferences. While
Mystriosuchus, similar to Paleorhinus, was semi-aquatic
and piscivorous, Nicrosaurus had a terrestrial lifestyle
and probably preyed on tetrapods. Comparing the habitats
of the different European phytosaur genera reported in
literature, it is also concluded, that Mystriosuchus and
Paleorhinus tolerated, contrary to Nicrosaurus, a wide
range of salinity.
K e y w o r d s : Phytosaurs, habitats, lifestyle,
Triassic, Norian, Arnstadt Formation.
Cerda, I.A. & Desojo, J.B., 2010.
Dermal armour histology of aetosaurs (Archosauria:
Pseudosuchia), from the Upper Triassic of Argentina and
Lethaia (Early View (Articles online in advance of print))
One of the most striking features documented in aetosaurs
is the presence of an extensive bony armour composed of
several osteoderms. Here, we analyse the bone
microstructure of these elements in some South American
Aetosaurinae aetosaurs, including Aetosauroides scagliai.
In general terms, Aetosaurinae osteoderms are compact
structures characterized by the presence of three tissue
types: a basal cortex of poorly vascularized parallel-
fibred bone tissue, a core of highly vascularized fibro-
lamellar bone, and an external cortex of rather avascular
lamellar bone tissue. Sharpey?s fibres are more visible
at the internal core, toward the lateral margins and
aligned parallel to the major axis of the dermal plate.
No evidence of metaplastic origin is reported in the
osteoderms, and we hypothesize an intramembranous
ossification for these elements. The bone tissue
distribution reveals that the development of the
osteoderm in Aetosaurinae starts in a position located
medial to the plate midpoint, and the main sites of
active osteogenesis occur towards the lateral and medial
edges of the plate. The osteoderm ornamentation is
originated and maintained by a process of resorption and
redeposition of the external cortex, which also includes
preferential bone deposition in some particular sites.
Given that no secondary reconstruction occurs in the
osteoderms, growth marks are well preserved and they
provide very important information regarding the relative
age and growth pattern of Aetosaurinae aetosaurs.
ERIC BUFFETAUT, ATTILA OSI and EDINA PRONDVA (2010)
The pterosaurian remains from the Grünbach Formation
(Campanian, Gosau Group) of Austria: a reappraisal
of 'Ornithocheirus buenzeli'.
Geological Magazine (advance publication)
The fragmentary pterosaur material from the Campanian
Grünbach Formation (Gosau Group) of Muthmannsdorf
(Austria), previously identified as Ornithocheirus
buenzeli Bunzel, 1871, is revised. A lower jaw fragment
shows a helical type of articulation, which is known in
several families of pterosaurs, and cannot be identified
with great accuracy. The proximal part of a humerus shows
distinctive features that allow it to be referred to as a
member of the family Azhdarchidae, which is widespread in
the Late Cretaceous Period of Europe. Ornithocheirus
buenzeli is considered a nomen dubium. The pterosaur
material from the Grünbach Formation cannot be used as
evidence for the presence of ornithocheirids in the Late
Cretaceous of Europe.