Magyarosuchus

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Magyarosuchus
Temporal range: Early Jurassic, Toarcian
Magyarosuchus skeletal.png
Skeletal reconstruction and size comparison, known remains in white.
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauria
Clade: Pseudosuchia
Clade: Crocodylomorpha
Suborder: Thalattosuchia
Superfamily: Metriorhynchoidea
Genus: Magyarosuchus
Ősi et al., 2018
Species:
M. fitosi
Binomial name
Magyarosuchus fitosi
Ősi et al., 2018

Magyarosuchus is an extinct monotypic genus of metriorhynchoid thalattosuchian described for the first time from fossils discovered in the Kisgerecse Marl Formation in Hungary. The type species Magyarosuchus fitosi lived during the Toarcian, about 180 million years ago. [1] It is known from a fragmentary skeleton discovered in 1996. [1]

Contents

Description

Magyarosuchus was a large thalattosuchian, the known partial jaw is deeper (taller) than other close relatives like Pelagosaurus, teeth on the lower jaw would've been oriented upwards and slightly out to the sides. Many isolated teeth are preserved in the holotype, these were large and recurved, possesing a circular cross-section and non-serrated edges, along vertically alligned grooves (fluting).

Some limb bones are known, these are similar to those known from other thalattosuchian relatives, its femur and tibia are 36 cm (14 in) and 21 cm (8.3 in) long respectively.

Many caudal vertebrae are preserved, the posterior-most one in the holoype; albeit incomplete, shows a noticeably larger neural spine than the ones before it. This might suggest the presence of a rudimentary vertical expansion (tail fluke) as its known in more derived metriorhynchid relatives.

Many partial osteoderms and some complete ones are known, these would've been arranged in two dorsal, and at least two ventral rows along the body. Each dorsal osteoderm overlapped the one behind it, they were mostly square, and possesed a small lateral ridge. The ventral osteoderms also overlapped front-to-back, and were tightly sutured to the ones besides them, these were much wider than long.

Evolution & Classification

Magyarosuchus is an early member of the clade Metriorhynchoidea. [1] These were the most marine-adapted group of thalattosuchians, with the later and more derived family Metriorhynchidae being fully marine, dolphin-like predators. [2] Magyarosuchus exhibited a mosaic of adaptations for offshore life alongside ancestral, non-marine traits. For instance, it retained body armor similar to that of earlier thalattosuchians and terrestrial crocodylomorphs. However unlike those animals, Magyarosuchus had a tail vertebra that may show the beginnings of a tail fluke. [1] Along its size (larger than any other non-metriorhynchid metriorhynchoid) this combination of traits show that Magyarosuchus represents a transitional form between the fully ocean going metriorhynchids and their earlier non-marine ancestors.

The cladogram below is from a 2024 study on the phylogenetic relationships of thalattosuchians. [2]

Metriorhynchoidea

Ecology

Magyarosuchus was discovered in the Kisgerecse Marl Formation, whose deposits indicate a more open-ocean environment. It represents the oldest known thalattosuchian adapted to such conditions, rather than to coastal or lagoonal habitats. The frequent occurrence of ammonite fossils in these rocks further supports that this ecosystem was an open ocean. [1]

The adaptations of Magyarosuchus for life in the open ocean, combined with the abundance of ammonite fossils in its environment, may suggest that it may have been a pursuit predator specializing in ammonites. [1]

References

  1. 1 2 3 4 5 6 Attila Ősi; Mark T. Young; András Galácz; Márton Rabi (2018). "A new crocodyliform thalattosuchian large body from the Lower Jurassic (Toarcian) of Hungary, with further evidence of the mosaic acquisition of marine adaptations in Metriorhynchoidea". PeerJ. 6 e4668. doi: 10.7717/peerj.4668 . PMC   5949208 . PMID   29761038.
  2. 1 2 Young, Mark T.; Wilberg, Eric W.; Johnson, Michela M.; Herrera, Yanina; De Andrade, Marco Brandalise; Brignon, Arnaud; Sachs, Sven; Abel, Pascal; Foffa, Davide; Fernández, Marta S.; Vignaud, Patrick; Cowgill, Thomas; Brusatte, Stephen L. (2024). "The history, systematics, and nomenclature of Thalattosuchia (Archosauria: Crocodylomorpha)". Zoological Journal of the Linnean Society. 200 (2): 547–617. doi: 10.1093/zoolinnean/zlad165 . hdl: 20.500.11820/a60965ed-4772-40be-9e95-fc09cfe646b1 .