Hallopus

Hallopus was a prehistoric reptile, named in 1877 as a species of Nanosaurus and classified by O. C. Marsh in 1881 as a dinosaur,[1] but now thought to be a pseudosuchian more closely related to crocodilians. It was a quite small animal, reaching a length of 1 m (3.3 ft).[2] It was redescribed as a sphenosuchian crocodylomorph.[3] Later, it was speculated to be more derived than Sphenosuchus and near or within the Junggarsuchus + Crocodyliformes node.[4]

Hallopus
Temporal range: Late Jurassic, 155.7–145.5 Ma
Hallopus victor front and hind limb
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Family: †Hallopodidae
Genus: †Hallopus
Marsh, 1881
Type species
†Hallopus victor
Synonyms

Phylogeny

A recent phylogenetic analysis[5] recovered Hallopus in a clade with Macelognathus and Almadasuchus, the Hallopodidae (defined as "all taxa more closely related to Hallopus victor than to Protosuchus richardsoni or Dibothrosuchus elaphros). The Hallopodidae was recovered as the nearest sister to the Crocodyliformes and more derived than Junggarsuchus or the "sphenosuchians" whose monophyly was not supported in this analysis.

Similarly, in redescribing Macelognathus from the Morrison Formation, Göhlich et al. (2005)[6] recognized several anatomical similarities between Macelognathus and Hallopus while also noting if the provenance of the latter was correct, they would overlap stratigraphically.

Restoration
Skeletal restoration

References
  1. O. C. Marsh. 1877. Notice of some new vertebrate fossils. American Journal of Arts and Sciences 14:249-256
  2. http://qilong.wordpress.com/2011/05/27/better-know-a-crocbeak-macelognathus-and-hallopus/
  3. A. D. Walker. A Revision of the Jurassic Reptile Hallopus victor (Marsh), with Remarks on the Classification of Crocodiles. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences Vol. 257, No. 816 (Feb. 26, 1970), pp. 323-372
  4. http://dml.cmnh.org/2004Sep/msg00097.html
  5. Leardi et al. (2017), Detailed anatomy of the braincase of Macelognathus vagans Marsh, 1884 (Archosauria, Crocodylomorpha) using high resolution tomography and new insights on basal crocodylomorph phylogeny. PeerJ 5:e2801; DOI 10.7717/peerj.2801
  6. Göhlich, U. B., Chiappe, L. M., Clark, J. M. & Sues, H.-D. 2005.The systematic position of the Late Jurassic alleged dinosaur Macelognathus (Crocodylomorpha: Sphenosuchia). Canadian Journal of Earth Sciences — Revue canadienne de sciences de la Terre 42(3):307-321.


This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.