Terrific Tetanurae 16: Betasuchus bredai

The wind dries the water spat onto the cold, grey trees by the waves to a salty brine as the sun heats the island already choked by heat. There are few trees here, as the island has been burnt through by fire and buried by floodwaters many times before. Fortunately for the animals which still cling to the isle, the ground shines green with flowers, moss, and ferns. Herds of dwarfed lambeosaurs traverse the land, scraping off the greenery from the pale earth. At their feet, coelurosaurs dash to and fro, eating insects which have been disturbed by the grazing hadrosaurs. Little dromaeosaurs, bearing distinct sickle claws, prowl the wilderness alone. The small size of the island prevents them from forming packs, in which competition would kill the feathered dinosaurs. Alone, they must be cautious, as larger predators stalk this island of dwarfs. 

Abelisaurs, short armed and blunt-headed carnivores, lie in wait next to water holes. These ten foot long killers are among the largest animals of the island, and are most easily able to bully dromaeosaurs away from kills. 

As a herd of hadrosaurs stops to drink, an unfortunate male is spotted by an abelisaur, which, like a bull, charges and rams into the hadrosaur. Dazed and bruised, the hadrosaur bellows for its herd, but all other dinosaurs have fled the scene in panic. The abelisaur continues to attack, finally forcing the hadrosaur down to the rugged ground, where it dies. 

The abelisaur barely gets a nibble of the hadrosaur carcass when a loud trumpeting sound is heard from the tree. Out of the blue bursts a theropod, though it is unlike the dromaeosaurs and abelisaurs of the island. It is a Betasuchus, a relative of tyrannosaurids. The theropod lunges at the abelisaur with its claws, its dark feathers trembling in the wind. The abelisaur, gored by the feathered theropod, trots away. If the wound becomes infected, the abelisaur may die. 

During the Cretaceous, Europe was reduced to scattered islands surrounded by tempestuous seas filled with whale-sized predators. Where France and Germany now are, ocean allowed but of few nesting grounds for terrestrial organisms. Limited ground meant that animals dependent on dry land could only get so large, dramatically changing the evolution of European Cretaceous dinosaurs. To the east, fossil remains from dinosaurs of Hateg Island provide remarkable glimpses into a world of miniature sauropods, tiny ornithopods, and gigantic pterosaurs. To the west, the remains of abelisaurs, such as Tarascosaurus, as well as those of dromaeosaurs, such as Pyroraptor, have been discovered. Looming in the ocean depths surrounding these islands were mosasaurs, giant marine squamates which hunted the abundant fish, invertebrate, and marine reptiles of the Cretaceous. These giants are well known from the Netherlands, where the type specimen of Mosasaurus hoffmannii was unearthed from a quarry in Maastricht.

Nearby, a more obscure predator left but one reminder of its existence. A partial femur, named Megalosaurus bredai, was described in 1883, and would be the first terrestrial Maastrichtian vertebrate known to science (Seeley, 1883). The name of the animal would later be changed to Betasuchus bredai  (Von Huene, 1932). 

There has been confusion over what type of theropod dinosaur the femur belongs to. It has been found to be from an ornithomimosaur, or “ostrich dinosaur” in a few studies (Von Huene, 1926)(Russell, 1972). However, the femur has also been considered to have come from an abelisaur (Loeuff  & Buffetaut, 1991)(Tykoski & Rowe, 2004). Abelisaurs were large predators of Europe during this time, with forms like Arcovenator appearing in France (Tortosa et. al., 2013).

IMG_3912

The skull of Majungasaurus, an abelisaurid dinosaur. Photo by the author, 2015.

Perhaps the most interesting classification of this animal has been as a relative of the Appalachian tyrannosauroid Dryptosaurus  (Carpenter et. al., 1997). This classification, if true, could have implications for the origin of Dryptosaurus aquilunguis  and other Appalachian tyrannosaurs like it. It would also paint a different picture of Betasuchus as a dwarf version of the 8 meter Appalachian predator, using large claws on its forearms as well as slicing teeth for handling prey.

The ecology of Betasuchus is just as obscure as the animal itself. However, a possibly diverse fauna of hadrosaurs from the Cretaceous of the Netherlands and northern Belgium. Two possible distinct lambeosaurine taxa, as well as a possible euhadrosaurian, may have lived alongside Betasuchus (Jagt et. al., 2003). An abelisaurian or dryptosaurian Betasuchus would likely have preyed on these hadrosaurs. Dromaeosaurs may have also existed alongside Betasuchus, as the group was present in Europe during the Late Cretaceous (e. g. Allain & Taquet, 2000).

IMG_3211

This is the partial leg of a juvenile Corythosaurus casuarius, a lambeosaurine dinosaur. Photo by the author, 2015.

Betasuchus bredai evinces the obscurity of some of the earliest known prehistoric vertebrates. The only known specimen, a partial femur, is a hint at an ancient island ecosystem where hadrosaurs roamed, pterosaurs stalked, and theropods hunted.

FullSizeRender.jpg

Betasuchus bredai by the author. Colored pencils on paper, 2015.

References

  1. Seeley, H. 1883. “On the dinosaurs from the Maastricht beds.” Quarterly  Journal of the Geological Society of London 39: 246-253.
  2. Von Huene, F. 1932. “Die fossile Reptil-Ordnung Saurischia, ihre Entwicklung und Geschichte.”Monographien zur Geologie und Palaeontologie  4: 1-361.
  3. Von Huene, F. 1926. “The carnivorous Saurischia in the Jura and Cretaceous formations, principally in Europe.”Revista del Museo de La Plata 29:35-167.
  4. Russell, D.A. 1972. “Ostrich dinosaurs from the Late Cretaceous of western Canada.” Canadian Journal of Earth Sciences 9: 375–402.
  5. Loeuff, J. & Buffetaut, E. 1991. “Tarascosaurus salluvicus nov. gen., nov. sp.,dinosaure théropode du Crétacé supérieur du Sud de la France.” Geobios 24 (5): 585-594.
  6. Tykoski, R.S. & Rowe, T., 2004.”Ceratosauria.” In: Weishampel, D. B.; Dodson,P.; and Osmólska, H. (eds.): The Dinosauria (2nd Edition) Berkeley: University of California Press. pp. 47-70.
  7. Tortosa, T.; Buffetaut, E.; Vialle, N.; Dutour, Y.; Turini, E.; Cheylan, G. 2013. “A new abelisaurid dinosaur from the Late Cretaceous of southern France: Palaeobiogeographical implications.” Annales de Paléontologie (advance online publication). doi: http://dx.doi.org/10.1016/j.annpal.2013.10.003
  8. Carpenter, K.; Russell, D.; Baird, D.; Denton, R. 1997. “Redescription of the holotype of Dryptosaurus aquilungis (Dinosauria: Theropoda) from the Upper Cretaceous of New Jersey.” Journal of Vertebrate Paleontology  17: 561–573.
  9. Jagt, J. W. M.; Mulder, E. W. A.; Schulp, A. S.; Dortangs, R. W.; Fraaije, R. H. B. 2003. “Dinosaurs from the Maastrichtian-type area (southeastern Netherlands, northeastern Belgium).” Palevol 2: 67–76.
  10.  Allain, R. & Taquet, P. 2000. “A new genus of Dromaeosauridae (Dinosauria, Theropoda) from the Upper Cretaceous of France.” Journal of Vertebrate Paleontology 20: 404-407.
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s