History of Paleomammology: The sabre-toothed moonrat from the island of the sabre-toothed prongdeer

In 1969 a team of palaeontologists, Cornelis Beets, Hendrik Schalke and Matthijs Freudenthal from the Dutch Rijksmuseum van Geologie en Mineralogie from Leiden, discovered and excavated various fossil lagerstätten in the fissures of the Mesozoic limestone of the Gargano promontory, exposed by the intense quarrying activities in the area. For three summers the team, aided also by other researchers from all over Europe, searched the red clays for bones and teeth of rodents, insectivores and artiodactyls.
One of the most intriguing specimens of the endemic fauna recovered was a large insectivore mammal, described in 1972 by Freudenthal as Deinogalerix and attributed to the family of the Erinaceidae, which includes modern hedgehogs and the moonrats.

Fig.1. The fossil material of Deinogalerix is actually composed by two sub-complete skeletons and hundreds of isolate teeth and bones, the first one was found in 1969 and is hosted today in the Nationaal Natuurhistorisch Museum of Leiden (from VILLIER et al.2009).

Moonrats today include only 7 species found in South-east Asia; they are large, ratlike animals lacking the characteristic spikes of the common hedgehogs - they most probably resemble best how the extinct Deinogalerix look alike.
However Deinogalerix displays the usual unusual characteristics of endemic mammals of islands - in contrasts to related fossil or recent mainland species it was a very large animal - 9 kilograms (this is a 2 kg rat of the the genus Mallomys, endemic to Indonesia) heavy and 60 centimetres long - not including the stumpy tail - with 20 centimetres skull - one of the largest insectivore known and the name emphasize the astonishment of the researchers realizing how large this strange animal was - they named it "terrible mouse".

Fig.2. and 3. Fragments of a left maxilla with three molars and of a right mandible with five molars of Deinogalerix compared to the respective bones of a modern hedgehog.

Various species (even if some of dubious taxonomic value and representing a possible sexual dimorphism) are described, all descending from the earliest known genus Parasorex originally of Asiatic origin: D. freudenthali, D. brevirostris, D. minor, D. intermedius and D. koenigswaldi - the last and biggest species of the genus.

Fig.4. The skulls of D. koenigswaldi and D. brevirostris compared to two actual species of insectivores: Echinosores gymnura (moonrat) and Erinaceus europaeus (hedgehog) (from VILLIER et al.2009) - for the size of the largest species - D. koenigswaldi - see also this reconstruction by artist M. Anton and for the impact on pop-culture also this alternative reconstruction...

Based on its size of D. koenigswaldi early research suggested that the dull animal was a scavenger, the dentition suggest however that Deinogalerix was an active predator, hunting insects, and helped by its size, also small vertebrates.
The former of island of Gargano lacked population of large carnivores, with the exception of rare fossil of crocodiles, an otter (Paralutra garganensis) and more common bird of preys no fossil evidence of active predators was discovered. Deinogalerix had therefore little competition to fear and over geologic time occupied the niche as one of the apex predators of the Gargano island environment.

Fig.5. and 6. "The exact nature of the species to which the above mentioned fossil remains belong was at first quite dubious: there are molars which on a superficial view might be attributed to an artiodactyl, premolars that might conceivably indicate a carnivore, and large caniniform incisors, all of them together in a skull over 20 cm long." FREUDENTHAL 1972
Skull reconstruction from VILLIER et al.2009, upper premolar from Deinogalerix from the "Red Clays" of Gargano.

The peculiar fauna of the Gargano was considered an isolated and endemic fauna, however in 1999 a fragmentary maxilla with the characteristic teeth of Deinogalerix freudenthali was found in the ossiferous breccia of Scontrone, a village of today Central Italy. This discovery suggests a paleogeographic connection, maybe trough an episodic land bridge or smaller islands of the island of Gargano to the European mainland.

Bibliography:

AGUSTI, J. & ANTON, M. (2002): Mammoths, Sabertooths, and Hominids - 65 Million Years of Mammalian Evolution in Europe. Columbia University Press: 313
FREUDENTHAL, M., (1972): Deinogalerix koenigswaldi nov. gen., nov. spec., a giant insectivore from the Neogene of Italy. Scripta Geologica 14: 1-19
GEER, A.v.d.; LYRAS, G.; VOS, J.d. & DERMITZAKIS, M. (2010): Evolution of Island Mammals - Adaption and Extinction of Placental Mammals on islands. Wiley-Blackwell: 479+26 plates
VILLIER, B.; OSTENDE, H. & PAVIA, M. (2009): Deinogalerix: a giant hedgehog from the Miocene. Poster-Abstract Giornate di Paleontologia IX Edizione - Apricena (FG), 28-31 maggio 2009.

Online Resources:

Anonymous (): Age of Mammals - Deinogalerix. (Accessed 11.07.2011)
Tupaia (17.01.2011): L’incredibile fauna dell’isola del Gargano, arcipelago Puglia. (Accessed 09.07.2011)