An exciting discovery has been made by an international team of paleontologists: a new species of worm lizard has been unearthed in Tunisia, representing the largest known member of the Amphisbaenia, a group of limbless reptiles that look like a cross between snakes and worms. This newly identified species, named Terastiodontosaurus marcelosanchezi, has a skull exceeding five centimeters in length—an unprecedented size among worm lizards.
The findings have been published in the Zoological Journal of the Linnean Society, bringing fresh insight into the evolutionary history of these unusual reptiles. Today’s worm lizards are mostly subterranean, tunneling through the earth with their compact, blunt-headed bodies. However, this new discovery hints at a very different way of life. The fossil of Terastiodontosaurus marcelosanchezi reveals unique adaptations that suggest it might have roamed above ground, unlike its modern counterparts. These adaptations include massive jaws and distinctive dental features that point to a specialized diet—likely focused on consuming snails, a feeding habit that has apparently endured for over 56 million years.
Worm lizards belong to a distinctive group known as Amphisbaenia, creatures that initially seem to have a head at each end of their long, slender bodies. This characteristic is, in fact, an evolutionary illusion; worm lizards have evolved to navigate in both directions through underground tunnels with ease, using their tail to aid in backwards movement. Their body shape is similar to that of an earthworm, an adaptation that helps them maneuver through tight underground spaces.
This new species was identified by a diverse team of scientists from around the world. The group was led by Prof. Dr. Georgios L. Georgalis of the Institute of Systematics and Evolution of Animals at the Polish Academy of Sciences in Krakow. Collaborators came from the Senckenberg Research Institute and Natural History Museum in Frankfurt, the Institut des Sciences de l’Évolution de Montpellier, the Muséum national d’Histoire naturelle in Paris, and Tunisia’s National Office of Mines. The identification of Terastiodontosaurus marcelosanchezi provides the first evidence of a worm lizard of such magnitude, with its skull size setting it apart from any other known species within the group.
According to Prof. Georgalis, the fossils of this newly found species are closely related to the contemporary checkerboard worm lizard. However, due to its considerable size, Terastiodontosaurus marcelosanchezi likely lived a semi-subterranean lifestyle, spending a portion of its life on the surface, unlike the predominantly underground habits of present-day species. This unique aspect of its behavior is attributed to its large size, which would have made exclusive subterranean living impractical.
Adding to the insights provided by this study, PD Dr. Krister Smith from the Senckenberg Research Institute and Natural History Museum in Frankfurt commented on the significance of the size of the new species. He noted that if worm lizards could reach sizes comparable to that of snakes, then Terastiodontosaurus marcelosanchezi would parallel the giant snake Titanoboa, which could grow up to 13 meters long. This suggests that the newly discovered worm lizard was significantly larger than its closest relatives. Dr. Smith also speculated that the unusually large size of the species was probably related to the higher global temperatures during the Eocene epoch, the time period from which the fossils date.
The researchers utilized advanced micro-computed tomography to analyze the fossil, allowing them to uncover the detailed anatomical features of this Eocene-era species. The study revealed striking dental characteristics that distinguish Terastiodontosaurus marcelosanchezi from other members of the Amphisbaenia. The species possesses a prominent upper jaw tooth, flat molars, and several other unique traits that suggest a specialized feeding behavior.
Prof. Georgalis noted that visually, the creature could be likened to the fictional “sandworm” from the famous Dune novels and films, with its massive jaw and formidable teeth. The robustness of the tooth enamel and the structure of the teeth suggest that this species had an extraordinary bite force, capable of crushing the hard shells of snails with ease. This implies that the diet of Terastiodontosaurus marcelosanchezi was heavily reliant on snails, a conclusion that draws a direct connection to the feeding habits of modern worm lizards.
Dr. Smith highlighted the continuity of this dietary preference over millions of years. Modern-day checkerboard worm lizards are known for their preference for snails, which they break open with their strong jaws. This study suggests that such dietary habits began more than 56 million years ago with species like Terastiodontosaurus marcelosanchezi. Despite significant environmental shifts over millennia, this lineage has maintained a remarkably stable ecological niche, specializing in snail consumption to the present day.
This discovery not only adds a new member to the family of Amphisbaenia but also offers a glimpse into the adaptability and evolutionary success of these mysterious reptiles. The persistence of their feeding strategy, despite changing climates and habitats, underscores the resilience and specialization of the worm lizard lineage, providing valuable insights into the evolutionary pressures and ecological dynamics that have shaped their unique form over millions of years.