A new species of ancient reptile has been named after spending more than 200 million years buried in the ground, adding to the growing collection of discoveries made from the fossil-rich Cromhall quarry in southern England. The species, named Threordatoth chasmatos, is an important addition to the fossil record, offering new insights into the procolophonids, an often-overlooked group of reptiles that lived during the Triassic period. These animals were part of an ancient lineage that survived the Permian mass extinction and thrived in the ecosystems of the early Mesozoic era.
Cromhall, located in South Gloucestershire, has long been recognized as a hotspot for Triassic fossils. The site has yielded numerous significant finds, including gliding reptiles, early dinosaur relatives, and some of the earliest known lizards. Over the past few decades, paleontologists have been able to gather a wealth of knowledge from the fossilized remains found in this area. Threordatoth chasmatos is the latest discovery to be added to the growing list of Triassic wildlife unearthed at Cromhall.
Dr. Luke Meade, the lead author of the study describing this new species, provides an intriguing description of the animal. He suggests that Threordatoth chasmatos likely resembled modern horned lizards, with bony spikes on its head and possibly bony armor covering its body. “I like to imagine them scampering around the sinkholes and fissures of southwest England in the Late Triassic, looking for plants and bugs to eat while avoiding the early relatives of dinosaurs,” says Meade. This image of a small, spiny reptile evoking the behavior of contemporary horned lizards adds a layer of imagination to the scientific study of ancient life.
The fossil evidence for Threordatoth chasmatos remains incomplete, with only parts of its jaw discovered so far. However, these fragments are highly significant because they offer valuable clues to understanding the procolophonids, a group of reptiles that are often poorly represented in the fossil record. Dr. Marc Jones, the Curator of Fossil Reptiles, notes that procolophonids were generally small, which made their bones particularly vulnerable to damage before the fossilization process could occur. Consequently, most of the fossils recovered from these animals are limited to teeth and jaw fragments, leaving paleontologists with many unanswered questions. However, the discovery of Threordatoth chasmatos has brought scientists one step closer to filling in the gaps about these enigmatic reptiles.
Threordatoth chasmatos belongs to a group of reptiles known as procolophonids, which first appeared around 260 million years ago. These reptiles were a prominent part of ecosystems from the end of the Permian period through to the Triassic. Despite their lizard-like appearance, procolophonids are not closely related to modern lizards. Instead, they are an example of convergent evolution, where unrelated species develop similar traits due to similar environmental pressures. It is believed that procolophonids are distant relatives of all modern reptiles and birds, but their evolutionary relationship to these groups remains somewhat unclear.
The procolophonids’ fossilized remains are often found in geological formations called fissure fills. These deposits are the result of ancient wildlife falling into rocky crevices, which were then sealed over by sediment and eventually turned into fossils. The fissures where these fossils are found are small, which means that the fossils within them tend to be relatively small as well. Despite the small size of the fossils, however, they are often exquisitely preserved, providing paleontologists with well-preserved examples of ancient life.
In the case of Threordatoth chasmatos, the fossils were scattered across several institutions, including the Natural History Museum, National Museums Scotland, the University of Aberdeen, and the University of Cambridge. Although these bones had been previously referenced by other scientists, they had not been thoroughly examined until recently. The research team employed a process of carefully removing layers of rock from the bones using weak acid, followed by CT scanning to gain a closer look at the fossilized remains. The distinctive features of the jaw and teeth convinced the team that these fossils represented a new species, Threordatoth chasmatos.
One of the most notable features of Threordatoth chasmatos is its jaw. Dr. Jones points out that the front of the jaw is not fused together, and there is no clear site where the two halves would have connected. This suggests that the jaw may have been connected by ligaments, making it somewhat flexible. Such flexibility could have been advantageous for the reptile, allowing it to absorb shocks when chewing and providing tooth-on-tooth contact during feeding. This adaptation would have been useful for an animal that consumed a variety of foods, including plants and insects.
Perhaps the most distinctive feature of Threordatoth chasmatos, however, is its teeth. The teeth of procolophonids are typically quite complex, with relatively thick enamel compared to other reptiles. This complexity has been suggested to have allowed procolophonids to process a range of food sources, from plants to insects. However, as time passed during the Triassic period, many procolophonids began to lose teeth, likely in response to a specialization in their diet. By the Late Triassic, most procolophonids had developed teeth with just two points, which may have enabled them to eat tougher, more fibrous plant material.
Threordatoth chasmatos takes this trend even further. Unlike its relatives, which typically had two-pointed teeth, this new species has teeth with three distinct points. This feature is so unique that the researchers named the species after the characteristic, using the Old English term “Threordatoth,” meaning “three-pointed teeth.” The only other procolophonid with teeth similar to this is Hwiccewyrm, another species discovered at the same quarry in Cromhall.
The findings of the research were published in the journal Papers in Palaeontology, and the study highlights the importance of continued investigation at sites like Cromhall. The quarry has already yielded a range of species from various groups, including early dinosaur relatives and gliding reptiles, and much more remains to be discovered. Meade explains that although significant discoveries have been made, there is still much to be explored in the quarry. The ongoing excavation and analysis of material from the site could reveal many more species, shedding light on the diversity of life during the Triassic period and further expanding our understanding of the procolophonids.
Procolophonids were an important part of Earth’s ecosystems during the Triassic, playing a key role in the aftermath of the Permian mass extinction, which wiped out a large portion of life on Earth. Their survival and diversification following this extinction event suggest that these reptiles were highly adaptable, able to occupy a range of ecological niches. While many of the procolophonids were small, plant-eating animals, others likely fed on insects or even small vertebrates. Over time, as the climate and ecosystems changed, procolophonids continued to evolve, with some species becoming more specialized in their feeding habits.
The study of procolophonids and other Triassic reptiles is crucial for understanding the evolution of life on Earth. These animals lived in a world that was in transition, with the rise of the dinosaurs and the evolution of early mammals. By studying fossils like those of Threordatoth chasmatos, paleontologists are able to piece together the complex web of life that existed during this pivotal period in Earth’s history.
In conclusion, the discovery of Threordatoth chasmatos is a significant contribution to our understanding of Triassic ecosystems and the diverse array of reptiles that once inhabited Earth. Its unique characteristics, particularly its teeth and jaw structure, set it apart from other procolophonids and provide important clues about the evolution of these ancient reptiles. As further excavations continue at the Cromhall quarry, it is likely that more species will be discovered, each adding another layer of knowledge about the lifeforms that lived during the Triassic period and the broader patterns of evolution that shaped the development of life on our planet.
Source: Natural History Museum