A fossil bone, hidden away for four decades, has been identified as Antarctica's first dinosaur fossil. The specimen, discovered during a 1985 expedition, has been confirmed as a tail bone belonging to a titanosaur, a group of long-necked sauropods that included the largest animals to ever walk the Earth.
The fossil was found on the Antarctic Peninsula in a rock layer known as the Santa Marta Formation, dating back approximately 82 million years to the Late Cretaceous period. This marks the only dinosaur fossil from the continent found in this specific geological layer.
Professor Paul Barrett of the Natural History Museum in London noted that while the fossil might appear unremarkable, it holds significant historical value as the first dinosaur bone identified from Antarctica. At the time of the titanosaur's existence, Antarctica was covered in lush temperate forests, providing abundant food for large herbivores. Scientists anticipate that further discoveries may be made as climate change causes ice to retreat, potentially revealing more about the continent's past biodiversity.
Antarctica's dinosaur fossil record is sparse due to the extensive ice cover, making fossil hunting exceptionally challenging. Known fossil sites are primarily located in the Transantarctic Mountains and the Antarctic Peninsula, where exposed rock along coastlines facilitates discovery.
The bone was initially collected by Dr. Mike Thomson as part of an expedition focused on characterizing rock layers for geological and paleontological research. At the time, the team was primarily searching for invertebrates like ammonites to help date the rock layers. Dr. Mark Evans, a paleontologist with the British Antarctic Survey (BAS), suggested that the original team might have mistakenly identified the bone as belonging to a marine reptile.
Evans himself identified the bone as a potential dinosaur fossil in the BAS collections and, upon closer examination, suspected it was a titanosaur tail vertebra. Cross-referencing with Dr. Thomson's field notes confirmed the initial suspicion that it was a large reptile, and further comparison with recently discovered dinosaur fossils solidified its identification.
While some titanosaurs could reach lengths of up to 121 feet and weigh 57 tons, this Antarctic specimen is believed to be a juvenile or a dwarf species, estimated to be between 19 to 23 feet long. The discovery provides insights into how dinosaurs migrated across the southern continents. The absence of titanosaur fossils in Australia and limited evidence in New Zealand suggest they may have traveled to these regions when they were connected as part of the supercontinent Gondwana. During this era, Gondwana, including Antarctica, experienced a warm climate despite its polar location, partly due to volcanic activity releasing carbon dioxide into the atmosphere.
Matthew Lamanna from the Carnegie Museum of Natural History highlighted the importance of museum collections, stating that this bone lay undiscovered in a drawer for decades until new research and expertise enabled its identification. This find underscores the value of preserving specimens, as they can yield new discoveries with evolving scientific methods.
The findings have been published in the journal Acta Palaeontologica Polonica. Titanosaurs, like the well-known Patagotitan mayorum, represent some of the largest land animals known, with Patagotitan specimens weighing up to 65 tons and measuring 121 feet in length. These colossal herbivores consumed vast quantities of plant matter daily. Experts believe their long necks were adapted for efficient feeding, allowing them to gulp leaves whole rather than chewing. The extinction of dinosaurs around 66 million years ago is widely attributed to an asteroid impact, evidenced by iridium layers in the fossil record and the discovery of the Chicxulub Crater in Mexico.