Machairognathus pensiviorensis

The land of Eurasia in the late Cretaceous was full with wonder and danger. The prehistoric beasts of old time roamed the land they claimed. One of the most notable was one creature, first discovered in Pensivior District of Southern Russia. A creature that would shake the ground with its every step, a predator that surpass everything we have ever seen by its size and its might. Its maw are filled with giant, dagger-liked teeth that would bring anyone witnessing it to their knees... The national animal of Pensivior, Machairognathus pensiviorensis...

In the a late winter... A group of farmers in Pensivior discovered a few strange rock stuck out of the ground around their orchard. The deeper invesigation flipped a long lost treasure out of the rock that beared it. A half complete fossil of an entire animal body. It was so large that it amazed everyone that had seen it. Its skull is as long as an entire body of a man, each of its sharp teeth is bigger than a banana. This animal surpass the size of the largest dragon humanity ever witnessed. Soon, paleontologist got to hold on the fossil. The conclusion is that they had found a new specie of Theropod dinosaur, a very big one...

Machairognathus became the name of this newly found specie, naming after the giant, dagger-liked teeth that filled both of its jaws. This animal is meatured to be 16 metres long and almost 5 metres at height, the biggest terrestial predator ever to be found. However, only one fossil was found at the time and there was no other biological evidence presented in its site. Life of Machairognathus remained mysterious, until... Anothers were uncovered...

Five more specimens later were uncovered further into the south, in the famouse digging site known as "Black Clay Formation", Austravia. The site also well known for the bearing of another famous large predatory dinosaur, Tyrannosaurus rex eurasiaticus, the Eurasian subspecies of T. rex, which another subspecie, Tyrannosaurus rex rex, were found earlier across the world in America continent.

These new specimens even if not as complete or as big as the first one, still in good form and with its well known environment, helped full filling the missing information of this prehistoric gigantic killer.

Machairognathus is a very large theropod. With its size, it surpass the former record holders such as Tyrannosaurus, several Carcharodontosaurids and Spinosaurids and may only be surpassed by weight by the mysterious giant semi-aquatic dinosaur, Spinosaurus aegyptiacus. This makes Machairognthus the officially biggest theropod dinosaur ever lived (Several gigantic douditheres from Marvellous Valley don't counted as they aren't known by the most part of the world.)

This dinosaur confused paleontologists about its place in taxonomy for a while. Due to its resemblance to Carcharodontosaurid dinosaur, it was put into said group for a while until several resemblance of its skull and Tyrannosaurid were recognized. This creature actually is in the more advance group of theropod, Tyrannosauridae,  group of predatory dinosaur that are widespread across the northern hemisphere in the late Creataceous. However, unlike most Tyrannosaurid. Machairognathus's skull is much flatter on the sides and its snout is more elongated than most of its cousin. The major part that makes this animal unique among its kind, however it its tooth. The tooth of Machairognathus is flat and long, with serrated edge, looking like shark's teeth. This feature was what make them being grouped with Carcharodontosaurid theropods for sometimes, however it is known to be convergent evolution of its dentition that just went the same way. But what persuade a Tyrannosaurid to look like a very distinct related animal more than its own kind?

Black Clay Formation also held lots of herbivorous dinosaurs back in its day. They were the potential preys of the predators they lived along side. One notable herbivore is the giant, long necked sauropods, known as Alamosaurus pensiviorensis, which was also found at Pensivior, the place where Machairognathus were first discovered as well. By learning from the shape of teeth, Machairognathus's teeth are very effective at cutting prey's flesh. Its serration sears through the thoughest skin of large animal and make it heavily bleed. Its long neck is powerful and probably use to drive its teeth into the prey, increasing the potential damage. However, other than its dentition and neck, the rest of its body aren't as menacing. Mechairognathus has rather elongated and low body. Its arms are short, even shorter than other Tyrannosaurids and seems not ot have any function in hunting. The legs are stumpier and shorter than most of its relatives', indicating that it was a rather slow moving animal and not quite agile as well. Most preys in its environment probably could easily flee from it, except for one... The very slow and lumbering sauropod. Its bleeding bite also work well on the large and less mobile prey with lots of area to land a bite on. The discovery of both predator and its long necked prey in the same area, even in the different location also supporting this. Machairognathus probably hunt by striking these slow moving prey with its sharp teeth and then let the preys to bleed out to their death. Interestingly, as this method of hunting also known from Carcharodontosaurid dinosaurs as well. The similar lifestyle probably lead two distant related dinosaurs to become similar to each other.

Due to its preference on sauropod, this also explains how two large predators could live along side each others in Black Clay Formation. While Machairognathus prefer hunting sauropods, Tyrannosaurus who doesn't have as effective weapon to do the same job, meanwhile, have the speed and agility enough to tackle smaller prey which would be dispatched instantly or very quickly by its bone crushing bite. Both predators probably don't have to compete much to live alongside each other until their doom at the end of Cretaceous. However, if the confrontation between the two great predators did occur, it would be intestesting to know the outcome...

Due to its impressive size and look. The dynasty of Pensivior had declared Machairognathus as the nation animal of Pensivior. It was one of a few dinosaurs that are lucky enough to have this honor. The creature itself may have been long gone, but its might will be told for generations.
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Machairognathus (c) TheJuras

Also a big thank for to let me use his Tyrannosaurus's picture to make the T. rex Silhouette used in this sheet!

Ps: This information is fictional and only loosely based on reality.