Fossil of Giant Lizard Described From Mammalian Collections
by AMNH on
After 8 million years in the ground and 90 years in the Museum’s collection of mammalian fossils, a large animal from the Greek island of Samos is being recognized as a new species—of lizard.
Several years ago, Dr. Nikos Solounias, a visiting researcher specializing in the fossil record of animals from Samos discovered lizard bones mixed in with mammalian fossils that Museum paleontologist Barnum Brown had collected from Greece in 1924. Solounias showed the lizard bones to Jack Conrad, a research associate in the Museum’s Division of Paleontology, who recognized them as those of a varanid, a giant lizard typified by the Komodo dragon. In a new paper in PLOS ONE published last week, Conrad and colleagues Ana Balcarel and Carl Mehling have identified the 30-odd bone fragments, which fit in a box 8 inches long, as the remains of the oldest giant lizard ever to walk the Earth. If proportioned like its relatives, the new species—Varanus amnhophilis, or the Samos dragon—was 6 feet long.
The lizard bones didn’t wind up in the mammalian collections by complete accident. The varanid fossil is “definitely [from] Samos,” Solounias says. “Every locale has a characteristic look, like the color of the bone [and] the matrix,” or the mass of rock in which fossils are embedded. Researchers think that the fossils were excavated together, that the animals died and were buried together, and, significantly, that they lived together—a highly unusual phenomenon.
Large lizards rarely live alongside mammals. Although a mature varanid is a fierce predator, it is vulnerable as an egg, and as a juvenile it’s both too big to hide and too small to win a fight. Early monitor lizards, from the Late Cretaceous, were small. Those that grew large did so on on islands, isolated from mammals. The mammals that live alongside the Komodo dragon on Indonesian islands, such as the goats that this varanid famously swallows whole, were introduced by humans in the last few thousand years.
“Africa is the only place where there are giant monitors that have evolved in the presence of placental mammal competitors," Conrad says.
Researchers think that the Samos dragon, however, lived among weasels, hyenas, and pigs. Conrad hypothesizes that, once it reached adulthood, the Samos dragon’s size allowed it to stand up to the mammalian competition.