July 31, 21:39

Ichthyosaur from Eromanga Sea Fed Pterosaur and Became Prey for Pliosaaur

Researchers described the fossil of a six-to-seven-meter ichthyosaur, Platypterygius australis, which inhabited the inland Eromanga Sea in Australia during the Early Cretaceous period, approximately 105–106 million years ago. Among the scattered bones of this ancient reptile, fossilized remains of stomach contents were found. Analysis of this content showed that shortly before P. australis died, it had swallowed a pterosaur. There are two versions: either the ichthyosaur caught the winged reptile on its own, or it fed on its carcass. This marks the first documented case of an ichthyosaur feeding on a pterosaur.

Periodically, paleontologists come across fossil remains of ancient animals containing coprolites—that is, preserved parts of stomach and intestinal contents. Such finds allow for the direct study of the diet and feeding behavior of long-extinct species. For example, previously, a coprolite was discovered belonging to a sauropod, young specimens of Diamantinasaurus matildae, which lived in Australia about 100 million years ago. Analysis of this sample confirmed that sauropods were herbivores and ingested food without much chewing.

A team of paleontologists led by Matt Andrew White from Northeastern University presented data on another discovery of a fossil animal with preserved gastrointestinal tract contents. The focus was on remains under identification number KK F1435, which were found in the Tulubook formation in Queensland, Australia. The age of this specimen is estimated at 105–106 million years. During that era, most of Australia was covered by the shallow inland Eromanga Sea.

Specimen KK F1435 consists of the remains of a large reptile, including a nearly complete skull with teeth and fragments of the postcranial skeleton, such as vertebrae, ribs, and limb bones. By studying this specimen, White and his colleagues classified the remains as belonging to the ichthyosaur Platypterygius australis of the family Ophthalmosauridae, which is well known to paleontologists and was described in 1972. It was established that this individual could reach a length of six to seven meters when alive.

About half a meter from the skull of KK F1435, White and his co-authors discovered a spherical mass, which they interpreted as fossilized stomach content that had fallen out of the abdominal cavity. From this structure, two fragments of pterosaur tooth bone from the family Anhangueridae were extracted, whose wingspan was presumably about four meters. The most likely scenario is that P. australis caught the pterosaur while it was flying over the sea and ate it. An alternative version suggests that the ichthyosaur fed on the carcass of a winged reptile that fell into the water.

According to researchers, this is the first known example of an ichthyosaur feeding on a pterosaur. Nevertheless, coprolites also contained (using neutron tomography) remains of more typical ichthyosaur food: several belemnites, as well as fish vertebrae and ribs and shell fragments. The stomach contents of P. australis indicate that members of this species, and possibly other Cretaceous ichthyosaurs, were generalist predators consuming a wide range of prey.

Notably, deep tooth marks were observed on the vertebrae of KK F1435, and some vertebrae were broken or missing. Judging by the size and shape of these marks, they were left by the pliosaaur Kronosaurus queenslandicus—an even larger marine reptile that reached over ten meters in length and occupied the position of apex predator in the Eromanga Sea. According to the most plausible version, the pliosaaur hunted the ichthyosaur, killed it, after which it fell to the seabed, damaging its skull from the impact. Then this same pliosaaur consumed the body of the victim, scattering the remains across the seabed over a distance of more than ten meters (possibly its relatives later acted as scavengers).

The research results demonstrate the presence of a complete food chain in the Eromanga Sea: large ichthyosaurs consumed mollusks, fish, and pterosaurs, and in turn became prey for more massive pliosaurs. Several years ago, paleontologists found a fragment of a lower jaw of an unknown pterosaur on the Tulubook formation, based on which a new genus and species—Thapunngaka shawi—was described. Scientists estimated the wingspan of this reptile to be six to seven meters, making it the largest pterosaur in Australia. There is a possibility that the bone found in P. australis's stomach belonged to T. shawi.

nplus1.ruJuly 31, 09:46

Paleontologists found well-preserved digestive system of a marine reptile that lived 245 million years ago

Scientists were able to discover and study the perfectly preserved digestive system of a marine reptile that inhabited Earth 245 million years ago. Specialists described an specimen of the archosauromorph Austronaga minuta, which existed in the Middle Triassic in the Yunnan province of China.

Details of the find and classification

Analysis confirmed that this species belonged to the family Trachelosauridae and led a marine lifestyle. In addition to skeletal remains, this animal had fossilized skin, muscles, blood vessels, as well as stomach, small and large intestines, and liver preserved. According to a publication in the journal Science Advances, this is the oldest preserved reptilian digestive system.

History of marine archosauromorphs

Archosaurids and other archosauromorphs have repeatedly inhabited the oceans. Among the most successful representatives are seabirds and Mesozoic Thalattosuchians, which are distant relatives of crocodiles. Some of the first marine archosauromorphs were members of the Middle Triassic families Tanystropheidae and Trachelosauridae, belonging to the recently identified clade Tanysauria, such as Tanystropheus with their very long necks. It is assumed that the transition of these two families to oceanic life occurred independently.

Study of Austronaga minuta

A team of scientists led by Wayne Van from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences presented new data on the marine tanysaur Austronaga minuta. This small species was first described by Van and his colleagues in 2023 based on a fossil specimen from Yunnan province—a limestone slab containing a skull, part of the neck, and tail. The age of the find was determined to be 245 million years, corresponding to the Middle Triassic. Since A. minuta was found in marine deposits, and its nostrils were shifted back from the snout, and it had conical teeth in its mouth, the discoverers hypothesized that it fed on fish and lived in the sea.

Full analysis of the specimen

In a subsequent study, Van and his team analyzed another limestone slab where missing parts of the same A. minuta specimen were found: a remnant of the neck (which turned out to be quite long), torso, limbs, and base of the tail. Analysis of the entire specimen confirmed the species' belonging to the tanysaurids, specifically the family Trachelosauridae. Its closest relative was Dinocephalosaurus orientalis, which also inhabited the seas of Yunnan at the same time.

Lifestyle and size of the reptile

Researchers, based on the complete skeleton of A. minuta, concluded that its length was only 60 centimeters, significantly smaller than the six-meter D. orientalis. However, it remains unclear whether an adult or juvenile specimen was studied. Scientists also found additional signs of a marine lifestyle: the forelimbs and hindlimbs, due to the proportions and structure of the bones (including elongated fingers due to extra phalanges), functioned as flippers for swimming. Furthermore, the scapula, coracoid, pubis, and ischium of A. minuta were thinned, resembling plates, which is characteristic of other marine reptiles. There was partial reduction of the pelvic girdle, which reduced its ability to support weight on land. It is likely that A. minuta swam excellently, using its tail for propulsion and its limbs as rudders, while its long neck helped it catch fish. Notably, its relative D. orientalis, despite living in the sea, did not have such strong adaptation to the aquatic environment.

Condition of internal organs

The second limestone slab preserved soft tissues of A. minuta: remnants of skin and muscles in the sacral region, as well as the stomach, small and large intestines, liver, and blood vessels. Traces of undigested food, presumably fish scales, were found in the intestine, further confirming A. minuta's aquatic lifestyle. Nevertheless, overall, the internal organs of this species did not show a high degree of specialization for marine life. The authors emphasize that A. minuta represents the oldest reptile whose digestive system has been preserved to this day.

Vulnerability of tanystropheids

Previously, paleontologists established that the excessively long necks of tanystropheid archosauromorphs made them easy prey for predators. This is confirmed by fossil remains of two such reptiles, preserved only as heads and parts of cervical vertebrae. Predators likely attacked them from above and behind, using a powerful bite to sever the cervical vertebrae, after which they would drag the head with part of the neck and eat the rest of the body.

Another paleontological find

In a separate study, paleontologists discovered a tooth of the fossil spiny sunfish Neocometes brunonis in a German clay pit. The age of this find was estimated at 11.58 million years, which refutes the previous opinion that spiny sunfish had completely disappeared from Europe 1.7 million years earlier. The description of this find was published in the journal Fossil Imprint.