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Allodaposuchus hulki, new species from Spain + crocodyliform tooth from Hungary (free pdfs)



Ben Creisler
bcreisler@gmail.com


Two new papers in open access PeerJ:


Albert G. Sellés (2015)
A new species of Allodaposuchus (Eusuchia, Crocodylia) from the
Maastrichtian (Late Cretaceous) of Spain: phylogenetic and
paleobiological implications.
PeerJ 3:e1171
doi: https://dx.doi.org/10.7717/peerj.1171
https://peerj.com/articles/1171/

Background. The Late Cretaceous is a keystone period to understand the
origin and early radiation of Crocodylia, the group containing all
extant lineages of crocodilians. Among the taxa described from the
latest Cretaceous of Europe, the genus Allodaposuchus is one of the
most common but also one of the most controversial. However, because
of its fragmentary record, several issues regarding its phylogenetic
emplacement and its ecology remain unsolved or unknown. The discovery
of a single specimen attributed to Allodaposuchus, represented by both
cranial and postcranial remains, from the Casa Fabà site (Tremp Basin,
NE Spain) in the lower red unit of the Tremp Fm. (early Maastrichtian,
Late Cretaceous) offers a unique opportunity to deepen in the
phylogenetic relationships of the group and its ecological features.

Methods. The specimen is described in detail, and CT scan of the skull
is performed in order to study the endocranial morphology as well as
paratympanic sinuses configuration. In addition, myological and
phylogenetic analyses are also carried out on the specimen for to shed
light in ecological and phylogenetic issues, respectively.

Results. The specimen described herein represents a new species,
Allodaposuchus hulki sp. nov., closely related to the Romanian A.
precedens. The CT scan of the skull revealed an unexpected
paratympanic sinuses configuration. Allosaposuchus hulki exhibits an
“anterodorsal tympanic sinus” not observed in any other extant or
extinct crocodilian. The caudal tympanic recesses are extremely
enlarged, and the expanded quadratic sinus seems to be connected to
the middle-ear channel. Phylogenetic analyses confirm the emplacement
of the informal taxonomic group ‘Allodaposuchia’ at the base of
Crocodylia, being considered the sister group of Borealosuchus and
Planocraniidae.

Discussion. Although this is a preliminary hypothesis, the unique
paratympanic configuration displayed by A. hulki suggests that it
could possess a high-specialized auditory system. Further, the large
cranial cavities could help to reduce the weight of the cranium.
Concerning the postcranial skeleton, Allodaposuchus hulki shows
massive and robust vertebrae and forelimb bones, suggesting it could
have a bulky body. The myological study performed on the anterior limb
elements supports this interpretation. In addition, several bone and
muscular features seem to point at a semi-erected position of the
forelimbs during terrestrial locomotion. Taking all the above results
into consideration, it seems plausible to suggest that A. hulki could
conduct large incursions out of the water and have a semi-terrestrial
lifestyle.

==

Attila Ősi, Márton Rabi & László Makádi (2015)
An enigmatic crocodyliform tooth from the bauxites of western Hungary
suggests hidden mesoeucrocodylian diversity in the Early Cretaceous
European archipelago.
PeerJ 3:e1160
doi: https://dx.doi.org/10.7717/peerj.1160
https://peerj.com/articles/1160/


Background. The Cretaceous of southern Europe was characterized by an
archipelago setting with faunas of mixed composition of endemic,
Laurasian and Gondwanan elements. However, little is known about the
relative timing of these faunal influences. The Lower Cretaceous of
East-Central Europe holds a great promise for understanding the
biogeographic history of Cretaceous European biotas because of the
former proximity of the area to Gondwana (as part of the Apulian
microcontinent). However, East-Central European vertebrates are
typically poorly known from this time period. Here, we report on a
ziphodont crocodyliform tooth discovered in the Lower Cretaceous
(Albian) Alsópere Bauxite Formation of Olaszfalu, western Hungary.

Methods. The morphology of the tooth is described and compared with
that of other similar Cretaceous crocodyliforms.

Results. Based on the triangular, slightly distally curved,
constricted and labiolingually flattened crown, the small,
subequal-sized true serrations on the carinae mesially and distally,
the longitudinal fluting labially, and the extended shelves along the
carinae lingually the tooth is most similar to some peirosaurid,
non-baurusuchian sebecosuchian, and uruguaysuchid notosuchians. In
addition, the paralligatorid Wannchampsus also possesses similar
anterior teeth, thus the Hungarian tooth is referred here to
Mesoeucrocodylia indet.

Discussion. Supposing a notosuchian affinity, this tooth is the
earliest occurrence of the group in Europe and one of the earliest in
Laurasia. In case of a paralligatorid relationship the Hungarian tooth
would represent their first European record, further expanding their
cosmopolitan distribution. In any case, the ziphodont tooth from the
Albian bauxite deposit of western Hungary belongs to a group still
unknown from the Early Cretaceous European archipelago and therefore
implies a hidden diversity of crocodyliforms in the area.