Ichthyosauria review and other new papers

[bh480@scn.org]

From: Ben Creisler
bh4802scn.org

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 
available at:
http://www.palaeodiversity.org/currentissue.htm
Note that the pdfs are free!

A number of papers might be of interest to some DML 
members:

MICHAEL W. MAISCH, 2010.
Phylogeny, systematics, and origin of the Ichthyosauria --
the state of the art.
Palaeodiversity 3: 151?214 (December 2010)

Abstract
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).  

Abstract
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 
Archosauria.

K e y w o r d s : Pterosauria, archosaur, dinosauromorph, 
phylogeny.


JULIEN KIMMIG & GERNOT ARP, 2010.
Phytosaur remains from the Norian Arnstadt Formation 
(Leine Valley, Germany), with reference to European 
phytosaur habitats.
Palaeodiversity 3: 215?224 (December 2010)

Abstract
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.

======
Also new:


Cerda, I.A. & Desojo, J.B., 2010.
Dermal armour histology of aetosaurs (Archosauria: 
Pseudosuchia), from the Upper Triassic of Argentina and 
Brazil. 
Lethaia (Early View (Articles online in advance of print))

DOI: 10.1111/j.1502-3931.2010.00252.x.
http://onlinelibrary.wiley.com/doi/10.1111/j.1502-
3931.2010.00252.x/abstract

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)
doi: 10.1017/S0016756810000981
http://128.232.233.5/action/displayAbstract?
fromPage=online&aid=7937439&fulltextType=RC&fileId=S001675
6810000981

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.