Crocodile-eating apex dinosaur reveals missing link in predator evolution

A fossil of the Patagonie windy plains revises your book on one of the most elusive groups of hunting dinosaurs. The newly discovered dinosaur, Joaquinaptor Casali, attacked the floodplates soggy in Argentina about 67 million years ago, just before an asteroid that ended the age of the dinosaurs.

Weighing almost a ton and measuring almost 23 feet in length, this meat eater was as much a muscular killer as a glimpse of how his loved ones lived towards the last chapter of the Cretaceous.

The discovery buzzes the researchers not only because the skeleton turned out to be unexpected, but also on a horrible find trapped in its jaws – the arm of a crocodile type reptile. It is a vengeful guttural overview in the diet of this predator Apex.

A remarkably complete skeleton

The fossil was found in 2019 in the Lago Colhué Huapi region of the Patagonia Central Patagonia. The training rocks are Maastrichtian Stage Cretaceous, bringing the life of the animal in a few million years of the global extinction event. This makes Joaquinaptor one of the youngest megaraptorides.

What is remarkable about this specimen is how it has survived the test of time. Most megaraptor fossils are fragmentary – sometimes a handful of bones at best – while this skeleton has kept a large part of the skull, jaws, vertebrae, ribs and front limbs and posterior limbs. The paleontologist of the Carnegie Museum of Natural History Matt Lamanna described it as “among the most full -known megaraptran skeletons of science”.

Anatomy designed for hunting

The megaraptorans were a family of carnivorous dinosaurs extinct, with three fingers and long arms which had huge claws on the hands and long heads. Joaquinaptor shared these same traits, with the exception of a pair of unexpected differences. Its humerus, the upper bone, was a thicker and unusually thick, suggesting muscles capable of making the flesh. The ulna, a bone from the forearm, had an extended process for the fixing of the muscles, giving the added force of the dinosaur in the arms.

His claws were large and slightly hung, well suited to the tear of the flesh but not to the cushion bone. The skull, reaching 28 inches in length, maintained rows of curved teeth which were small enough for a predator of such a size. This strange combination indicates an animal that uses its powerful arms and claws as much as its bite.

The fossil was estimated at 19 years, as determined from microscopic growth rings in its bones. Like trees, these lines are a chronicle of annual growth cycles. The distance between them revealed that the dinosaur had slowed growth, having probably reached sexual maturity but still not at full adult size.

A clue in its jaws

Perhaps the most dramatic part of the discovery was not dinosaur itself, but what he had in a trailer. Between his teeth was the bone from the top of the crocodyliform arm, a parent of today’s crocodiles. Some of the Joaquinaptor teeth were blocked against the bone, and paleontologists have observed clear bite brands.

Lucio Ibirici, the first author of the study, said that evidence strongly supports that crocodiles were on the menu. Whether it’s chasing the reptile or recovering your leftovers is not certain. Even some experts show the possibility that the predator was killed in his attempt to eat it. “Megaraptorans are perhaps the most mysterious dinosaurs of all,” said Ibiricu. “The croc bone could give us our first clear indication of what they ate.”

A predator’s place in the food canvas

At the end of the Cretaceous, the Patagonia environments were dominated by the megaraptorides, as opposed to northern South America, which was dominated by other predators such as Abélisaurides. This regional split represents “provincialism” – the idea that different groups of dinosaurs have prospered in the geographic provinces.

Joaquinaptor probably attacked young titanosaurs, long -neck plants who dominated the region and the Hadrosaurs with a beak. The CROC member is proof that his diet was more diverse, perhaps even including reptiles sharing the same wetland habitat.

The flood plain beach where she lived was hot and humid, with lagoons and rivers forming the landscape. Pasts that were drier are represented by lower cases of the same training, suggesting megaraptorides developed over millions of years to adapt to changing conditions.

Close but different from tyrannosaurs

Evolutionary analysis places the megaraptorans near the tyrannosaur line, the family that produced the tyrannosaurus rex. But the two families were as different as day and night. While T. Rex relied on a huge skull, destroyed teeth and puny arms, Joaquinaptor included longer jaws, smaller teeth and massive and striking forearms.

This suggests that these two lines of predatory dinosaurs have evolved different answers to do the same task – Kill and capture prey, “said Lamanna.” This shows that there was more than one way of being an Apex predator. “”

Fill the scalable gaps

The discovery of Joaquinaptor Casali pushes the previously established existence of megaraptorides near the end of the Cretaceous, almost a million years before the impact of asteroids. Its well -preserved skeleton establishes a standard for the comparison of other fragmentary fossils, filling gaps in the information that scientists have concerning this mysterious group.

The study also highlights models of megaraptorid growth. Like most dinosaurs, they have never stopped growth even after reaching sexual maturity, which means that adults could really be in size. It is estimated that some of the cousins ​​of Joaquinaptor in Patagonia lasted more than 26 feet.

The name of the dinosaur is a recognition of science and family. “Joaquin” is a recognition of the son of Ibirici, and “Casali” is a recognition of Gabriel Andrés Casal, a geologist who helped to understand the units of the Cretaceous of Patagonia.

Practical research implications

This discovery highlights the evolution and adaptation of large predators through South America and reveals new levels of diversity only a few moments before mass extinction.

By examining the growth rings and the bone composition, the researchers also discover more about the life cycles of dinosaurs to model the way in which ecosystems responded to environmental change.

The member of Crocodile strangely preserved in the jaws of dinosaurs offers a particular view of the old predators-roots, shedding light on food networks towards the end of the age of dinosaurs.

These results allow researchers to reproduce how ecosystems react to massive disturbances, which could be applied to contemporary biodiversity emergencies.

Research results are available online in the journal Nature Communications.

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