Ancient animals such as tyrannosaurs and woolly mammoths have remained in the spotlight of our pop culture for many years. They have appeared in countless books, movies, video games, and other forms of media. However, until the past two decades, scientists were only able to draw assumptions about an animal's appearance by examining its skeleton.
This often led to misunderstandings and incorrect depictions of extinct animals in the media. Scientists also had no way of confirming or disproving beliefs about their diets, lifestyles, and body functions.
Over the years, climate changes have led to the discoveries of many well-preserved animal mummies, and advancements in technology have enabled researchers to better analyze the specimens. Some of these specimens are almost completely intact, despite being many thousands of years old.
They still contain skin, hair, and muscle tissue. Scientists have even managed to extract liquid blood samples from a handful of animals. The findings have finally made it possible for scientists to create accurate representations of these specimens and better understand their lifestyles.
This article discusses the following incredible animal mummies and what we have learned from them:
- Borealopelta, the 110-Million-Year-Old Ankylosaur
- Leonardo, the 77-Million-Year-Old Brachylophosaurus
- Zhùr, the 57,000-Year-Old Gray Wolf Puppy
- Yuka, the 39,000-Year-Old Woolly Mammoth
- Sasha, the 34,000-Year-Old Woolly Rhinoceros
1. Borealopelta, the 110-Million-Year-Old Ankylosaur
Borealopelta was discovered in 2011 at the Millennium Mine, an oil sands mine located 30 kilometers (19 miles) north of Fort McMurray in Alberta, Canada. This fascinating ankylosaur has been identified as a new dinosaur species, spanning about 5.5 meters (18 feet) in length and weighing 1.5 tons (3,000 pounds).
It was a four-legged herbivore that possessed the thick, heavy armor of other ankylosaurids but lacked a club at the end of its tail. The specimen lived 110 to 112 million years ago, during the early Cretaceous Period.
Scientists believe that Borealopelta drowned in a flood and was pulled out to sea before it was entombed in a thick layer of sediment. The animal's body cavity became filled with sand, and a siderite concretion formed around the carcass, which prevented scavengers from consuming it.
Borealopelta is one of the best-preserved dinosaurs of its size. This specimen's osteoderms (armor plates) remain in their life positions. It also still possesses keratin sheaths, overlying skin, and stomach contents from its last meal. Besides this, Borealopelta's skin contains traces of chemicals called benzothiazoles that have led some scientists to believe the animal was mostly reddish-brown with a light-colored underside.
Countershading (in which the upper side of an animal is dark in coloration and the underside is lighter) is a common trick used by today's small, terrestrial prey to make them appear flat and inconspicuous. Once a prey animal grows large enough, its size usually provides enough defense against predators, and it doesn't need to rely on camouflage anymore. This explains why animals like elephants and rhinos are solid gray in color.
However, Borealopelta may defy that trend. If this large, heavily-armored dinosaur did indeed rely on countershading as well, it would mean that size and armor did not always provide adequate protection from Cretaceous predators.
It may seem obvious that large predators hunted herbivores like Borealopelta. However, some people believe that armoured dinosaurs were predator-proof. In order for a predator to take down one of these ankylosaurs, it would have to flip the herbivore onto its back, which likely was a difficult task due to its size and weight. Nevertheless, it seems that enough predators were doing this to drive the evolution of countershading in ankylosaurs.
Besides possible evidence of camouflage, researchers also discovered some useful information about Borealopelta's diet. While freeing the animal from its rocky tomb, they found a football-sized mass in its abdomen that appeared to be a cololite.
The mass contained a few gastroliths (rocks that the dinosaur intentionally swallowed to help break down plant matter in its stomach). An examination of Borealopelta's stomach indicated that ferns were a significant part of its diet, and it ate small amounts of palm-like cycads and conifer needles as well.
Fern leaves constituted about 85 percent of the animal's stomach contents and belonged to only one type. This is quite surprising, considering the fact that there was a wide variety of fern species growing in the region where Borealopelta likely lived.
That means this ankylosaur must have been reasonably picky. The fossilized stomach contents also support scientists' long-held belief that dinosaurs fed on ferns, and Borealopelta has provided some of the first hard evidence for fern-eating.
Roughly six percent of Borealopelta's stomach contents contained charcoal as well, meaning it had ingested plant material from an area that was experiencing some regrowth after a recent wildfire. Researchers deduced that the ferns were halfway through their growing season before being ingested, which means the ankylosaur likely ate them in early or mid-summer and died a few hours after its meal.
2. Leonardo, the 77-Million-Year-Old Brachylophosaurus
Leonardo, also known as specimen JRF 115H, is a fully articulated and partially mummified skeleton of an adolescent Brachylophosaurus. It was discovered in 2000 in Malta, Montana but was not excavated until 2001. The animal was about seven meters (23 feet) long, possibly weighing two tons (4,000 pounds) at the time of its death.
Researchers have estimated that this dinosaur lived 77 million years ago and was around four years old when it took its last breath. The consensus is that Leonardo collapsed into the water after it died, which helped to preserve much of its soft tissue.
This specimen is one of the most impressive dinosaurs ever discovered, and it was even featured in the Guinness Book of World Records. Fossilized soft tissue covers around 90 percent of Leonardo's body. The remarkable animal still possesses skin, scales, muscle tissue, nail material, foot pads, and a beak.
Researchers discovered skin impressions on the underside of Leonardo's skull and along its legs, ribcage, left arm, and neck. Its throat tissue and right shoulder muscle remain intact. 2-D and 3-D X-rayed images have indicated that some internal organs may still exist as well.
The examination of Leonardo's well-preserved body has allowed scientists to conclude that the base of this species' neck was heavily muscled. They also found that the soft tissue of the upper neck was placed in an elevated position and ran much higher than was previously depicted in drawings. Artists' reconstructions initially just followed the curvature of the vertebral column while filling much of the bend between dinosaur's back area and head.
Leonardo's back possesses a midline frill consisting of triangular or hatchet-shaped projections. These projections appear to be separated individually from one another and are positioned as extensions of each of the vertebral column's neural spines. The second, third, and fourth digits of the specimen's hand are covered by a soft tissue "mitten."
Its shoulder muscle is well-preserved and can help scientists calculate the range of motion it had. Scientists can also use their findings to determine the size of this animal's step, how its chest muscles functioned, and if it truly walked on all four legs.
A 2008 study of Leonardo indicated that Brachylophosaurus' diet consisted of leaves, ferns, conifers, and flowering plants like magnolias. Surprisingly, its stomach contained pollen from over 40 different plants. The study concluded that Brachylophosaurus was a generalist herbivore, meaning it was both a browser and a grazer.
However, its stomach contents prove that it tended to be more of a browser. It is also quite important to note that aquatic plants did not constitute the majority of this animal's diet, which disproves the long-held theory that hadrosaurs (duck-billed dinosaurs) like Leonardo spent most of their lives in or near water and fed exclusively on aquatic vegetation.
Researchers also found parasites in Leonardo's stomach. The parasites were small, needle-like worms covered in thin bristles. This discovery indicates that similar parasites likely infested other dinosaur species.
3. Zhùr, the 57,000-Year-Old Gray Wolf Puppy
Zhùr was discovered in 2016 on the ancestral land of the local Tr'ondëk Hwëch'in people in northern Canada. This specimen's name means "wolf" in the community's language, and it has been identified as the oldest, most complete wolf mummy ever found. Zhùr is almost 100% intact, only missing its eyes and some fur.
The secret to its astonishing preservation is the permafrost that it remained sealed in for thousands of years. The permafrost protected it from air and moisture damage, allowing scientists to reconstruct this animal's life in impressive detail.
Scientists have confirmed Zhùr was a female, and X-rays indicated that the puppy was only around six or seven weeks old when she died. Geochemical signatures on Zhùr's teeth revealed that her diet consisted of fish and other aquatic animals rather than terrestrial prey such as caribou or bison. This evidence suggests she lived her short life during the summer months when fish like salmon would have been more plentiful and easily accessible.
Researchers also found that Zhùr was in good shape; her death was not the result of starvation or an attack by another predator. Rather, it is likely that this specimen was in her den when it collapsed, trapping her inside and possibly suffocating her.
Zhùr has provided a glimpse into the lives of wolves that resided in the Yukon territory thousands of years ago. An analysis of this puppy's DNA indicated that she descends from an ancient wolf population which were the ancestors of gray wolves. These ancestors originated from present-day Siberia, Russia, and Alaska.
Like modern gray wolves on the Alaska Peninsula, ancient wolves in the Yukon area appear to have dined heavily on seafood during warmer months. In the summer, they likely lived close to estuaries and other bodies of water, making a meal of whatever aquatic prey they could catch. Fatty foods like salmon would have been particularly beneficial to puppies, especially before autumn when food was a bit more scarce and they needed to put on extra weight for the colder months.
DNA sampling and isotopic measurements revealed that Zhùr is related to ice age wolves from Europe and only distantly related to modern North American wolves. The evidence proves that different wolf populations were mixing with one another across the Bering land bridge. However, Zhùr's population does not exist in the Yukon region anymore. This was the first wolf population to inhabit the region, and scientists have deduced that it was wiped out and replaced by another one.
Despite the fact that ice age wolves like Zhùr were from the same species as present-day gray wolves and possibly shared some similarities in lifestyle, researchers have discovered that they are not as genetically similar to their modern relatives as one might expect them to be.
4. Yuka, the 39,000-Year-Old Woolly Mammoth
Yuka, a young female mammoth, is known as the best-preserved mammoth mummy ever found. She was discovered in 2010 on the southern coast of the Laptev Sea (located in the Yakutia region of Russia's Arctic coast) and was extracted from permanently frozen soil and ice.
The specimen has been on display in Moscow, Russia since October 2014, where she is being kept at freezing temperatures in a special glass case in order to prevent her body from decomposing.
Yuka differs from other woolly mammoth mummies in that she is quite large for a specimen so well-preserved. In previous years, only baby mammoths had been discovered with much of their hair, soft tissue, and internal organs intact. The young adult Yuka stands three meters (9.8 feet) tall and weighs five tonnes (11,023 pounds), which is over four times larger than most of the other well-preserved mammoths that were recovered from the permafrost.
An analysis of Yuka's teeth and tusks indicated that she was approximately six to eleven years old when she took her last breath. Scientists found that the mammoth had suffered a broken leg prior to her death, and they also identified scars on her body. This suggests she had been attacked by lions or other predators.
However, no evidence was discovered to support the theory that the predators had actually killed her. Besides the broken leg and scars, scientists also found that Yuka's skull apparently had been removed by human hunters. The specimen's skull was discovered separately from her body.
Many researchers believe Yuka fell into the water and drowned or got stuck in a swamp and died when she was not capable of freeing herself. Evidence to support one of these deaths lies in the fact that the lower part of her body was preserved quite well, including her lower jaw and tongue tissue.
The mammoth's upper torso and two legs (which were in the soil) had been chewed by both prehistoric and modern predators and almost did not survive. Her brain and foot pads are extremely well-preserved. Yuka's body also still retains large patches of reddish-brown and blonde hair.
Yuka's brain is currently the only mostly intact mammoth brain known to science, and it is in such good condition that the folds and blood vessels are still visible. It also contains traces of nervous tissue and a well-preserved dura mater (a dense membrane that protects the brain).
Researchers were able to study her cerebellum and forebrain using CT (computed tomography) and MRI (magnetic resonance imaging) scans. They could see the white and gray matter of the cerebrum, but the forebrain was more difficult to examine due to its slightly poor condition.
The specimen's brain is stained brown as a result of oxidation. Its volume is also 45 percent smaller than the volume of the cranial cavity (the space inside the skull which houses the brain). This means that Yuka's brain had shrunk significantly, possibly due to her body being stored at inconsistent temperatures when she was transferred to multiple facilities.
Scientists discovered that her brain's structure is similar to that of a modern elephant. This is not surprising, as modern elephants are related to mammoths, and both species belong to the family Elephantidae.
Besides the discovery of a well-preserved brain, scientists were also able to find and extract liquid blood from Yuka, which was the first time they managed to do so. The team of scientists believes mammoth blood contains a kind of natural anti-freeze.
Since the mammoth is in such exceptional condition and possesses large numbers of undamaged cells, some researchers have proposed to use the cells to resurrect the ancient species. Scientists in South Korea have taken up a major interest in Yuka and even signed a deal giving them rights to attempt to clone the specimen.
During one experiment, the nuclei of Yuka's muscle cells were transferred into living mouse oocytes. Five of these nuclei actually showed signs of biological activity after the transfer and had reactions that usually occur right before cell division. However, the cell division itself never occurred, and the nuclei became dormant again.
While the general public may be convinced that a real-life Jurassic Park with woolly mammoths is a likely event of the near future, researchers are doubtful that they will ever be able to bring a true mammoth back into this world. Many scientists have argued it is impossible to find or construct a complete, viable mammoth genome simply by using cells from mummies like Yuka.
5. Sasha, the 34,000-Year-Old Woolly Rhinoceros
Sasha was discovered in Siberia's Yakutia region in 2014. This specimen currently is the only baby woolly rhinoceros ever found, and scientists have confirmed that it lived about 34,000 years ago. They have also estimated Sasha's age at seven to eighteen months but are not sure if it was a male or female. It is highly likely the infant died from drowning, as its nasal passages were clogged with mud.
Not only is Sasha the only baby woolly rhino ever found, but it is also known as the best-preserved woolly rhino in the world. Sasha's head is in good condition, with its eyes, ears, tongue, and two horns all preserved. The animal's front and rear legs remain intact as well, and it has retained almost all of its skin and hair.
Sasha's extraordinary coat has helped prove woolly rhinos were covered in thick hair, which initially could only be discerned by studying cave paintings. It also proves they were fully adapted to the cold climate at a young age.
The specimen is around 1.5 meters (4.9 feet) long and 0.8 meter (2.6 feet) tall, which is about the size of a modern 18-month-old African rhino. The discovery of Sasha gives researchers the opportunity to compare it with modern rhinos and determine how close they are to one another on the evolutionary path.
After a series of studies, researchers have found that human hunters were not responsible for the extinction of the woolly rhino. It was initially believed that humans appeared in northeastern Siberia 14,000 to 15,000 years ago, which is around the time when the woolly rhino became extinct.
However, there have been several recent discoveries of much older human settlements. The most famous one is about 30,000 years old, proving that their extinction does not coincide with the first appearance of humans in the region. In fact, there actually seems to have been a slight increase in the woolly rhino population at the time.
Scientists examined DNA extracted from the soft tissue, bones, and hair of multiple woolly rhino specimens in order to learn about the size and stability of their population in Siberia throughout the millennia. Based on data collected by the researchers, it appears that climate change played the most significant role in the disappearance of the woolly rhino.
Besides studying the DNA samples of woolly rhinos, scientists also sequenced the complete nuclear genome of woolly mammoths and 14 mitochondrial genomes to estimate the female effective population sizes. By examining the genetic diversity of the genomes, they were able to estimate the woolly rhino populations for tens of thousands of years prior to their extinction. The team also looked at changes in their population size and estimated levels of inbreeding within the populations.
The researchers discovered that there was an increase in the woolly rhino population at the beginning of a cold period about 29,000 years ago. After this, the population size remained constant, and inbreeding was low. It is also important to note that the population's stability lasted well after the appearance of humans in Siberia. The data collected by scientists only goes back to 18,500 years ago (which is 4,500 years before their extinction), implying that they declined sometime within that gap.
The data also revealed genetic mutations which helped woolly rhinos adapt to colder weather and possibly contributed to their decline. One mutation, a type of receptor in the skin for sensing warm and cold temperatures, was discovered in woolly mammoths as well. Many researchers believe woolly rhinos declined during a brief warming period known as the Bølling-Allerød interstadial.
During that period, the climate was considerably warmer than it is today, and it appears to coincide with their extinction towards the end of the last ice age. While human involvement cannot be completely ruled out, researchers have suggested that the woolly rhino's extinction was more likely a result of climate change.
- A Dinosaur So Well Preserved, It Looks Like a Statue | The Atlantic
Borealopelta, discovered accidentally by Canadian miners, is one of the most spectacular fossil finds of all time.
- Fossil stomach reveals a dinosaur’s last meal | Science News for Students
- "Mummified" Dinosaur Discovered In Montana | Biology Online Archive Article
Leonardo, a mummified, 77-million-year-old duck-billed dinosaur was only about three or four years old when he died, but he's proving to be a bonanza for paleontologists today.
- Ancient mummified wolf cub in Canada 'lived 56,000 years ago' | BBC
Scientists say the cub, which died about 56,000 years ago, is "the most complete wolf mummy known".
- World's best-preserved woolly mammoth goes on display in Moscow | Daily Mail Online
The baby woolly mammoth, named Yuka by scientists, was found by hunters on Russia's Arctic coast in 2010. It still has clumps of hair preserved due to being trapped in ice.
- Woolly rhinoceros baby Sasha is three times older than thought | Daily Mail Online
Called Sasha, the well-preserved calf was discovered last year preserved in permafrost in the far north of Siberia in 2014.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2022 Lisa Pizzoferrato