The greatest and most comprehensive remains of a prehistoric superpredator- but one that existed hundreds of thousands of years before SUE, the Tyrannosaurus rex. - can be seen at the Field Museum in Chicago.

Whatcheeria was one lake-dwelling species six feet long with a salamander-like shape and a long, slender head; its bones have been uncovered in a stone quarry close to the town of What Cheer, Iowa. And about 350 Whatcheeria specimens were discovered, spanning from single bones to full skeletons, and everyone is housed in the Field Museum's collections.

These fossils helped show how Whatcheeria became large enough to threaten its marine food in recent research published in Communications Biology: rather than being "slow and steady" like several other current reptiles as amphibians, it developed quickly in its maturity.

Whatcheeria: The Apex Predator of its Era

Hypothetically, encountering a Whatcheeria in person in the present times, it really would resemble a large crocodile-shaped salamander with such a narrow face and a lot of teeth, as per Ben Otoo, a co-author of the paper as well as a Ph.D. candidate the University of Chicago and also the Field Museum.

This was due to Whatcheeria's status as an apex predator. It lived underwater, as evidenced by bony grooves in its cranium for sensory systems similar to aquatic and fish amphibians, and its robust leg bones may have allowed it to hunker down in one area and wait for prey to swim past. As per Otoo, it would have spent enormous time around the depths of streams and lakes, leaping out and consuming anything it wanted. One may name this predator "the T." rex of its era.

Whatcheeria seems to be a big salamander, but it isn't. It's a stemmed tetrapod, a primitive four-legged species that developed further into four-limbed animals humans see today. Whatcheeria is more closely linked to contemporary tetrapods like frogs, reptiles, and mammals than anything else, yet it falls outside of those current groupings, as per Ken Angielczyk, a researcher at the Field Museum and co-founder of the study. That implies it can help experts understand how tetrapods, including themself, developed.

Scientists may examine the animal at various stages of its life since the Field contains so many Whatcheeria fossils. Several early tetrapods are documented from a single skeleton, or in many cases, a remnant of a single bone, according to Angielczyk. However, scientists have identified species variation since there are so many Whatcheeria in the Field. Some Whatcheeria are approximately six and a half feet in length, whereas others are considerably smaller. That implies there was a chance to investigate how they developed.

Sawing open the behemoth’s bones revealed they got big quick to survive in a dangerous aquatic environment.
(Photo: Nobu Tamura, CC BY-SA 3.0)
Sawing open the behemoth’s bones revealed they got big quick to survive in a dangerous aquatic environment. Whatcheeria was a whole unit two-meters long with bone crushing jaw strength.

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Growing in Younger Years

Analyzing these remains is like going through a novel, and we're attempting to read as many more pages as they can by seeing how juveniles develop into adults, said Megan Whitney, the study's primary researcher, a lecturer at Loyola University in Chicago who started working on the research at Harvard University. Scientists decided to focus on Whatcheeria due to its position in the earliest tetrapod family tree.

Otoo and Angielczyk provided thigh bones from 9 Whatcheeria people ranging in age from juvenile to adult to study growth. Whitney and her adviser, Harvard University's Stephanie Pierce, examined small slices of bone under a microscope. Every growth season, an animal generates new layers of bone, per Otoo.

They say that one may see a seasonal rhythm in which the animal grows rapidly in the spring and summer, then slows down in the winter and resumes growth the next spring. By studying whether those growth rings are throughout an animal's life, one may determine if the animal is developing continually, with occasional breaks, or just expanding to adult size.

Some contemporary tetrapods, such as birds and mammals, develop rapidly as juveniles and plateau when they reach maturity. Other creatures, such as crocodiles and many amphibians, continue to develop slowly throughout their lifetimes. The researchers anticipated Whatcheeria to develop more like amphibians and reptiles "slow and steady," but Whitney discovered evidence indicating Whatcheeria expanded fast as it was young, then leveled out over time. She discovered fibrolamellar bone, primary bone tissue linked with rapid development.

Enormous Size as Strategic Advantage

Alongside Stephanie Pierce, they defied all of the norms they thought of for how development is developing in these early tetrapods, as Whitney recalled. The finding sheds light on some aspects of Whatcheeria's life. If it's going to be an apex predator, a huge animal, being big rapidly can be a strategic advantage since it makes it simpler to catch other animals and harder for some other predators to pursue another, as mentioned by Pierce.

It can also be a useful survival tactic when living in uncertain surroundings, such as Whatcheeria's lake system, which had a seasonal dying duration. Nevertheless, there is a cost: getting incredibly big fast requires a lot of energy, which might be a dilemma if there isn't enough food or other resources for the developing animal.

Scientists believe the discoveries, as well as helping humans understand the evolutionary forces on early tetrapods, are a lesson that evolution isn't a clean sequential process: it's a series of trials, as reported by Eurekalert.

As per Angielczyk, evolution seems to be about testing alternative lifestyles with feature combinations. As a result, one gets a creature like Whatcheeria, an early tetrapod but also a rather fast-growing one. It's rather large for its period. This strange skeleton may allow it to perform things that its contemporaries could not. It's a study of how to be a large predator and demonstrates how diversified life was and remains on Earth, Angielczyk concluded.

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