During the Triassic period, about 248 to 206 million years ago, mammals and dinosaurs emerged from different groups of equivalent-sized reptiles. As a result, dinosaurs evolved into large plant-eaters or carnivorous predators. At the same time, most mammals were relegated to a marginal existence.
In the era of dinosaurs, most mammals were little creatures. These mammals were nocturnal and fed on even smaller animals like insects, after which they would cower into their hidings to avoid being preyed on by the giant dinosaurs.
However, recent fossil discoveries have indicated that some of these mammals had large body sizes and even preyed on young and relatively more minor dinosaurs. These 130-million-year-old fossils have changed thinking about mammalian life during the Mesozoic Era.
Among these mammals that fed on dinosaurs is the gigantic ancient badger called the Repenomamus. Read on to learn more about it.
Description And Size
Repenomamus could be likened to modern-day badgers. Repenomamus possessed a barrel-shaped body that was relatively long and fubsy. The animal possessed a moderately-sized skull that was conical and had large jaws. Being a mammal, its entire body would have been covered in fur.
In terms of appendages, the Repenomamus possessed four relatively short legs. Their limb bones had a sprawling posture and ended in plantigrade feet. The animal’s body ended in a relatively long tail. Animals that belonged to the species of Repenomamus were the largest mammals that existed in the Mesozoic era, as indicated by fossil records.
Some species of Repenomamus, specifically the Repenomamus robustus, had the size of the present Virginia opossum. This species had a mass of about 4-6kg(8.8 -13lb). Animals that belonged to Repenomamus giganticus were almost twice as large as Repenomamus robustus, with a length of about 1m ( over 3 ft), and weighed about 12-14 kg (26-31 lbs).
These findings indicate that these Mesozoic mammals were larger than several moderately-sized dinosaurs. Even though Repenomamus looked like other therian mammals, the animal possessed a proportionally longer body with shorter limbs
What did Repenomamus Eat?
This gigantic ancient badger was a predator, and its food included primitive birds, lizards, and smaller dinosaurs. Whether Repenomamus preyed on live dinosaurs that were susceptible or scavenged on dead dinosaurs is unsure.
Nevertheless, either scenario might have been possible. Repenomamus was gigantic and fierce enough to catch and kill juvenile dinosaurs. Repenomamus had a heterodont dentition, equipped with sharp incisors and canines for tearing flesh. Pointed premolars for piercing and grasping prey.
Even at that, there’s no reason such a voracious mammal would have ignored the fresh body of a dead dinosaur. This was contrary to the usual narrative that many Mesozoic mammals were prey to dinosaurs and not the other way round as it is now.
Furthermore, the large and pointed incisors of Repenomamus allowed it to chew rigid plant materials or scrape at the body of dinosaurs.
Repenomamus was known for its hyper-carnivorous lifestyle. Its relatively gigantic size implied that it could hunt down small animals and feast on them without even breaking a sweat. Its teeth were such that it could easily tear and pierce through the flesh of its prey, and its jaws had enough bite force to sometimes smash through bones.
This claim was further strengthened when the remains of a Repenomamus giganticus was found with an infant Psittacosaurus in its abdominal region. The juvenile dinosaur was found in bits and pieces, indicating that the mammal tore it into little digestible bits before swallowing it.
When and Where Did Repenomamus Live?
Repenomamus is a prehistoric mammal which existed about 130 million to 125 million years ago during the Early Cretaceous Period in modern-day Asia. Fossils of these gigantic mammals were first discovered around the 21st century in the Yixian Formation in Liaoning, China.
It is believed that some species of these sturdily built mammals, specifically Repenomamus giganticus and Repenomamus robustus, lived in China about 130 million years ago. This dates to about 65 million years before we thought such animals existed on Earth.
Threats and Predators Of Repenomamus
The threats faced by Repenomamus would mainly be the environmental hazards of the Cretaceous Period. The weather conditions of the Cretaceous period were much warmer than we have today. It was probably the warmest of any era. There was a noticeable temperature difference between the poles and equator.
Temperatures were at the minimum at the beginning of the Early Cretaceous period, rising to a maximum in the mid-Cretaceous and then declining periodically until a more prominent cooling during the last two ages of the period. Moreover, the absence of ice sheets and glaciers made the Cretaceous Period much warmer.
Although there are no recorded predators or Repenomamus, the giant carnivorous dinosaurs like tyrannosaurus and Spinosaurus would have likely preyed on them.
Where Were Repenomamus Fossils Found?
Most fossils of Repenomamus were discovered in the lagerstätte of the Yixian Formation in the Liaoning province of China. This region is famous for its remarkably well-preserved fossils of feathered and winged dinosaurs.
Radiocarbon dating has indicated that the Repenomamus Fossils were about 125 million years old. This connotes that they existed during the Cretaceous Period.
Why Did Repenomamus Become extinct?
It is believed that Repenomamus must have gone extinct with the dinosaurs at the end of the Cretaceous Period due to the massive asteroid that hit the earth during this period.
Scientists believe the asteroid’s impact would have given rise to a tremendous dust cloud that encircled the earth. The dust cloud must have significantly reduced the amount of sunlight on the Earth’s surface.
The amount of sunlight reaching the earth was insignificant; hence plants died. So, no plant sources of food for Repenomamus. Animals were also wiped out, including Repenomamus, by the impact of the asteroid.
Other Animals That Preyed On Dinosaurs
Repenomamus wasn’t the only ancient animal that fed on dinosaurs. Other animals also did.
Deinosuchus was an ancient crocodile that existed during the Cretaceous Period. The animal was about 35 feet long and resided mainly in North America. Deinosuchus had the habit of preying on herbivorous dinosaurs that were munching on plants close to the river banks.
Paleontologists have unearthed comminuted bones of mid-sized dinosaurs that had tooth marks of Deinosuchus. However, whether Deinosuchus attacked these dinosaurs directly or scavenged on their bodies is uncertain. There is evidence that supports claims that Deinosuchus attacks large-sized dinosaurs.
The dinosaur-eating habits of Didelphodon are circumstantial. Based on their skull architecture, Didelphodons possessed jaws that could deliver one of the strongest bites among any Mesozoic animal. Their bites were bone-crushing and lethal.
Scientists came to a rational conclusion that Didelphodon munched on juvenile dinosaurs, as well as susceptible larger dinosaurs.
Even sea creatures weren’t left out of the game. Cretoxyrhina was a group of ancient sharks that existed about 100-75 million years ago. These giant sharks lived during the Cretaceous Period along with several large and dangerous creatures in the sea and on land.
In an age where every giant animal wanted to dominate, Cretoxyrhina was among the apex predators even though it wasn’t the biggest animal. Fossil records have shown that Cretoxyrhina was fierce and fearless. The teeth of Cretoxyrhina were like the Ginsu sword; hence they were named Ginsu sharks.
Cretoxyrhina had About 490 sharp teeth that are considered to have been believed to pierce flesh and crush bones easily. Fossils of several dinosaurs with shark marks point to Cretoxyrhina. These dinosaurs either missed their way or drowned in water bodies containing Cretoxyrhina.
Sanajeh is an ancient and monstrous snake about 10 feet long with a very thick body. The feeding strategy of Sanajeh was peculiar. The monstrous snake didn’t feed on mid-size or giant dinosaurs; instead, it would locate the nesting sites of titanosaur dinosaurs and devour the eggs.
Sanajeh also devoured unfortunate hatchlings. This feeding habit was backed up when paleontologists discovered a Sanajeh specimen wrapped around a titanosaur egg in India. At that same spot, the hatchling of titanosaur dinosaurs was also unearthed.
Mosasaurus was another apex predator during the Jurassic period. An enormous Mosasaurus would drag an Indominus rex to a watery grave. Even though the largest Mosasaurus specimens were about ten times smaller than the monster of Jurassic World, it still took up a fight with them.
Mosasaurs would have attacked dinosaurs that accidentally fell in the water during storms, floods, or migrations. Just like their ancient marine colleagues, the Cretoxyrhina, they had dinosaurs on their dinner menu
During the Cretaceous Period, giant pterosaurs also existed. Among these pterosaurs was the outstanding Quetzalcoatlus. This animal possessed a wingspan of about 35span and weighed 600 pounds. With this weight, one would question whether it was capable of active flight.
However, being a terrestrial animal that wandered across North America on its two hind feet, Quetzalcoatlus would have had dinosaurs on its food list. Not the giant dinosaurs, but the more little and juvenile dinosaurs, as well as the hatchlings.
Discover more secrets evolution has to offer. Understanding what ancient animals have existed helps to appreciate today’s ecosystem better. We offer more articles on ancient animals and events on this site.
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FAQs (Frequently Asked Questions)
When Was Repenomamus Alive?
Repenomamus is an ancient mammal that existed about 130 to 125 million years ago during the Cretaceous Period.
How Big Was Repenomamus?
Most Repenomamus had variable sizes. However, they were about 3ft long and were bigger than most feathered dinosaurs of the Cretaceous Period.
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