Leading de-extinction scientists say making use of genetic material more than a million years old won't be possible. Since the last male northern white rhino — a year-old called Sudan — died earlier in , elderly females Najon and Fatu are the last of their kind. But scientists hope that embryos in deep freeze could bring the "functionally extinct" species back from the edge. They were created in vitro from the sperm of a deceased male northern white and the eggs of the closely related southern white.
When the dodo — a fatally trusting and tasty bird — disappered from Mauritius in the 17th century, few believed mankind could extinguish the life of an entire species. Only after 19th century naturalist Georges Cuvier proved extinction was possible did the dodo became a symbol of that destructive power.
Now, the hunt is on for dodo DNA, in the hope we may also prove our power to resurrect. By the time the last Pyrenean ibex Celia died in , scientists had already gathered and frozen her tissue cells. Three years later, a goat gave birth to Celia's clone, created by injecting her DNA into a goat's egg. In fact, dozens of hybrid eggs were implanted.
Only seven animals became pregnant, and one carried to full term — and the resurrected ibex survived only a few minutes after birth. This is Martha, the last passenger pigeon, who died in The plump North American birds were a favorite for the plate, and hunting combined with deforestation wiped them out even as conservationists warned of their senseless demise.
European colonists in Australia put a bounty on the head of the thylacine, or Tasmanian tiger, a marsupial apex predator. The last known member of the species died in Hobart Zoo in Now, scientists have decoded the animal's entire genome from a joey preserved in ethanol, and hope to insert its genes into the DNA of its closest surviving relative, a diminutive marsupial called the numbat.
The most impressive species with any chance of making a comeback is the woolly mammoth, whose closest living relative is the Asian elephant. Scientists at Harvard University say the ice-age giants could play a role in slowing permafrost melt and, therefore, climate change.
But their "Pleistocene Park" concept would need 80, animals to have any real impact — pure science fiction, say critics. The auroch once roamed the length and breadth of Eurasia, but hunting and habitat loss wiped them out close to years ago. Yet their descendents — domesticated cattle — live on, and "back-breeding" programs have tried to resurrect the auroch by selecting for characteristics of the wild ancestor.
This graph shows the bite force of T. Bite force values of the reptiles are from: Erickson, et al. The Sharks are from: Wroe, et al. Most dinosaurs from this table are from: Bates and Falkingham For a 40 foot animal, they are only about the length of human arms. While other theropods, such as the Ornithomimosaurs, were developing long arms, all of the large Tyrannosaurs across the globe had developed very short and stubby arms. A quick look makes many people think they were useless and vestigial, and therefore they simply shrunk in size.
However, the rest of T. It would be strange to see a very specialized body plan that contains small useless arms. A closer look at the few fossil arms of T.
Also, Lipkin and Cerpenter found that T. An image of very muscular, shortened arms with large claws shouts specialization. They were not vestigial. If they were highly specialized, like the rest of T.
This is a diagram of a Tyrannosaurus rex arm. This work is by Conty Public Domain. Rothschild and Molnar investigated Tyrannosaur arms. They looked for stress fractures in the arms of T.
What's the big deal about stress fractures? A stress fracture is different from a break. Stress fractures occur during high impact and repeated activities. For example, stress fractures are not uncommon in people training for a marathon. Stress fractures occur with extensive use or overuse, not because of trauma. This means T.
So, what did T. This is where speculation comes to play. They could have been used for some sort of mating behavior. Perhaps they helped T. The speculation goes on and on. Rothschild and Molnar , tried to tackle this question. When looking at predators, stress fractures occur in their limbs when holding onto struggling prey. Previously, in , Rothschild and others studied the numerous stress fractures in the limbs of Allosaurus, a Jurassic theropod.
They concluded this theropod actively used its arms and legs to hold and grasp struggling prey. Rothschild and Molnar came to the same conclusion about T. Short muscular arms with large claws could hold the prey steady while the giant, bone crushing, jaws tore through the struggling dinosaur. Lipkin and Carpenter also support this. They note that the many injuries to the dinosaurs' shoulders were probably the result of predator-prey interactions. So, based on the research, what were T.
To hold onto struggling prey. Click on the link to view the full article. This figure shows body mass vs top speeds from the simulations. Tyrannosaurus rex is on the far right. The fastest theropod on thier chart is Compsognathus, a tiny 1m long critter. The best way to gauge the speed of a dinosaur is to study dinosaurs tracks. Unfortunately, there is a lack of Tyrannosaurus tracks.
There have been a few isolated footprints found in the western U. There have only been two trackways discovered so far. It was excavated between and and published in McCrea et al, This trackway consists of 3 individual Tyrannosaurs walking together.
Based on the gate of one of the trackways, it has been deduced that one of the Tyrannosaurs was walking between 6. Unfortunately, this trackway is of Tyrannosaurs walking, not running. So the running speed from this trackway cannot be determined. It was discovered near the Paleon Museum in Glenrock years ago, and with the help of Scott Persons, was recently researched and published on. These tracks are either of a juvenile T.
Calculations based on the tracks give a speed of between 4. Like the previous tracks, these tracks are of a fast walking or trotting dinosaur. So, again, the running speed of a T. However, when compared to other dinosaurs, T. Until further trackways are found, we must rely on other methods to deduce the maximum speed of a Tyrannosaur, such as the anatomy and physiology of the legs and tail, as discussed below.
Image of one of the Tyrannosaurus' tracks. Photo by Scott Persons, one of the papers authors: Smith et al, In the past, T.
It was often thought that due to its size, overcoming its own inertia would be difficult to do. If it could not move as fast as its prey, T.
Walking speeds from the two trackways gives walking speeds around mph, but say nothing about it's running speed. This is where musculoskeletal models come into play. This figure shows the reconstructed tail musculature. The M. A larger retractor muscle indicates a faster animal.
Tryannosaurus had a large M. A paper published in by Sellers and Manning shows that T. They developed musculoskeletal computer models of three living animals including a human as well as for five theropod dinosaurs. The speeds calculated for the three living animals were "in reasonably good agreement with accepted values.
A table of their data is shown above. Sellers and Manning conclude that improved musculoskeletal models will produce even more accurate values. Later, in , a more accurate T. They looked at both the leg structure and the unique tail structure of theropod dinosaurs.
Theropods have tails with a structure unlike any living animal today. Persons and Currie realized the tails weren't simply a large counterbalance, but an extension of the dinosaur's leg muscles. Some of the large tail muscles gave extra power to the dinosaurs' legs.
These extra muscles also added mass to the tail which would help center the inertia of the animal center of mass. They say Tyrannosaurus had a "sizeable investment in locomotive muscle among theropods. This evidence suggests a much more mobile and agile animal capable of chasing down prey Persons and Currie, In light of this new evidence, it appears T. So, when all the evidence is considered, it appears T. The debate as to whether or not T.
Most paleontologists agree that T. This conclusion is not only drawn from fossils but also from looking at predators today. There is no black and white line that separates a "predator" from a "scavenger.
To clarify, one can take a look at living carnivores. A good example is the lion and hyena. The Lion The lion is traditionally thought of as an apex predator in southern Africa. The Hyena On the flip side, the hyena is traditionally thought of as a scavenger. However, it has been found that many hyenas hunt for most of their food. However, neither is a pure predator or scavenger.
They are opportunistic carnivores. If one researches almost any apex carnivore, one will find they are a mix of both. So, it doesn't really makes sense to group T. Like most carnivores, it was probably a mix of both. How much it hunted vs scavanged will never be known. However, science tells us T. Below discusses some of the predator traits T. Although the skull is slightly crushed, one can see the eyes clearly look forward.
This is a key trait of most active hunters. Physical trace evidence of T. There have been many dinosaurs found with tooth marks, tooth pieces, and bite marks from T. A study of T. There have been many digested dinosaur bones found at fossil T. Bite and scrape marks from T. This means they ate each other! However all of this evidence simply shows T. However, a paper by DePalma et al , studied a T.
The interesting thing about this embedded tooth is the tail vertebra began to heal over. DePalma's team believes the T. Besides the sparse trace evidence of predation, one can study the actual anatomy of T. Looking at the various specialized body parts suggests it was a well designed predator. The jaws had the strongest bite force of any land animal ever. Paleontologists argue these overly strong jaws and solid teeth would be ideal for capturing and holding struggling prey, even a large hadrosaur or triceratops.
The dinosaur has forward facing eyes, not eyes on the sides of the head. Forward facing eyes gives an animal depth perception and is a key trademark of predators. As we now know, the tail of T. This is Figure 2 from McCrea et al. The full article with more images is here: doi In a paper was published by McCrea et al.
Chance of an answer: Nil. The only thing that would prove it is a Mesozoic-era recording of the creature. When Osborn described T. If in fact they were feathered, plumage could play a role in precopulatory courting rituals, extending that entertaining image. In order to pin down the logistics of how these 7-ton animals mated and reproduced, paleontologists need to know which fossils are male and which are female.
Unfortunately, T. However, in , Schweitzer found evidence in a Tyrannosaurus rex from the Hell Creek Formation of medullary bone, a type of tissue that accumulates in female birds during ovulation. This type of bone develops to provide calcium to the eggshell. The mysterious function of T. But scientists too have been perplexed by the dichotomy of such a large animal with such tiny, seemingly useless forelimbs.
Similar to the initial idea that T. As far as current theories go, the idea that T. Chance of an answer: Not out of the realm of possibility. Though the dinosaur hall will be closing on April 28, visitors will still get a peak at the Nation's T. In a special room at the National Museum of Natural History dubbed "the Rex room," museum conservationists will document, photograph, 3D-scan and store the skeleton before it is shipped off for exhibit assembly.
The museum will also feature a number of other exhibits on T. Smithsonian Associates will also be holding a special evening lecture on the Nation's T.
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