Friday, April 19, 2013

[Paleontology • 2013] Dahalokely tokana • An abelisauroid theropod dinosaur from the Turonian of Madagascar | New carnivorous dinosaur from Madagascar raises more questions than it answers

 Dahalokely tokana, holotype 


Geophysical evidence strongly supports the complete isolation of India and Madagascar (Indo-Madagascar) by ~100 million years ago, though sparse terrestrial fossil records from these regions prior to ~70 million years ago have limited insights into their biogeographic history during the Cretaceous. A new theropod dinosaur, Dahalokely tokana, from Turonian-aged (~90 million years old) strata of northernmost Madagascar is represented by a partial axial column. Autapomorphies include a prominently convex prezygoepipophyseal lamina on cervical vertebrae and a divided infraprezygapophyseal fossa through the mid-dorsal region, among others. Phylogenetic analysis definitively recovers the species as an abelisauroid theropod and weakly as a noasaurid. Dahalokely is the only known dinosaur from the interval during which Indo-Madagascar likely existed as a distinct landmass, but more complete material is needed to evaluate whether or not it is more closely related to later abelisauroids of Indo-Madagascar or those known elsewhere in Gondwana.

Outline of Dahalokely tokana with a human for scale,
showing known bones in white and missing areas patterned after related animals.

Figure 2. Dahalokely tokana, holotype (UA 9855)

Etymology: The generic name, from the Malagasy dahalo (bandit) and kely (small), references the small size of the animal relative to many abelisauroids. The species epithet, tokana (Malagasy, lonely), references the organism’s isolation on the landmass of Indo-Madagascar. The suggested, generalized pronunciation based on the Malagasy language is “dah-HAH-loo-KAY-lee too-KAH-nah.”

New carnivorous dinosaur from Madagascar raises more questions than it answers
The first new dinosaur named from Madagascar in nearly a decade, Dahalokely tokana was a carnivore measuring 9-14 feet long. Its fossils were found in 90-million-year-old rocks of northernmost Madagascar, from the time when Madagascar and India were a single isolated land mass. Dahalokely is potentially ancestral to later dinosaurs of both regions, and shortens a 95-million-year gap in Madagascar's dinosaur fossil record by 20 million years.

Farke, A. A., and J. J. W. Sertich. 2013. An abelisauroid theropod dinosaur from the Turonian of Madagascar. PLOS ONE. 8(4). doi: