A. altai might seem wimpy, but its more delicate features may have been the key to surviving alongside its bigger, badder brother, Tarbosaurus. “Different skull shapes and different bodies probably allowed Alioramus and Tarbosaurus to coexist” much as lions and cheetahs share the African grasslands today, Brusatte comments. Whereas Tarbosaurus probably pursued large animals using brute force, Alioramus could have snagged smaller animals using the speed and stealth that its smaller proportions allowed. In the lush forests of Late Cretaceous Mongolia, Alioramus would have had plenty of manageable prey to choose from, including numerous species of small dinosaurs.
The new A. altai fossil resolves an enduring mystery about a genus that scientists previously knew from a single fragmentary and poorly described specimen, named Alioramus remotus. Based on the earlier find, researchers had debated whether Alioramus was a primitive tyrannosaur ancestor or a more derived creature possibly related to T. rex. Some investigators even wondered whether it was a distinct genus at all, suggesting that the creature could just be a juvenile Tarbosaurus. But analysis of the new specimen, which is much more complete, reveals a creature that is very closely related to T. rex, despite lacking the hallmark tyrannosaur traits.
Questions remain about Alioramus, however. Holtz notes that researchers will need to find an adult Alioramus to assess to what extent the animal’s unusual features are the result of having a slower growth rate than larger tyrannosaurs versus simply stopping growth earlier.
Note: This article was originally printed with the title, "Tinier Tyrannosaurs."
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7 Comments
Add CommentT-Rex = Scavenger.
Reply | Report Abuse | Link to thisIs it really a "re-thinking" to suggest that T-Rex descended from a smaller animal with similar features instead of a similar size animal with different features? Why would it be assumed that the size came before the distinct features?
Reply | Report Abuse | Link to thisI take issue with the "certainty" that is usually portrayed in this type of article. Note the following quote:
Reply | Report Abuse | Link to thisUnearthed in Inner Mongolia, Raptorex lived 125 million years ago—60 million years before T. rex terrorized North America.
In reality, the author does NOT know for sure if Raptorex lived 125 million years ago. Also, there is NO certainty that T-Rex terrorized anything more than local plant leaves. Remember the Panda Bear's actual canine-like teeth and its actual vegetarian diet.
"T-Rex=Scavenger"
Reply | Report Abuse | Link to thisThere is no particular reason to think that T-rex was just a scavenger. Surely they would steel food from lesser species just as lions do today; that makes sense from an energy expenditure point of view.
My theory about T-rex and the like though, whether big or small, is that the strange little forearms are not an adaptation to running, because none of the mammalian top predators have this feature and most of them can run very fast. No I think those small forelimbs are an adaptation to the hideous side-sweeping tail hammers of ankylosaurs and the like. If enough herbivores developed means of damaging the forelimbs of their predators then advantage would go to the predators which could balance on their hind legs and lean over the defense to bite the neck of the prey or grab onto the front of its face to smother it.
ok, guys...first of all, dating fossils is very accurate now...down to the hundreds of thousands of years or so, which, geologically speaking, is akin to us speaking in days. second, T rex was absolutly NOT a scavenger, but like all predators would be an opportunistic feeder. The article is not saying that noone thought the huge Tyrannosaurs evolved from smaller ancestors, it is illustrating the similarity of body design and tracing the evolution of the family...all large dinosaur families had ancestors on the "small" side. as far as the arms, um, in modern predatory mammals it is absolutly an adaptation for speed. cats and canines rely on a combination of coordination of 4 legs and trunk muscles to achieve high speed. large Tyrannosaur arms were probably an adaptation to compensate for their larger heads (relative to body size) and to reduce weight. modern cats rely on their arms for holding prey as do some members of the canine family, although not as much...Tyrannosaurs did not need this function to be present as they relied on their superior bite force and enlarged neck muscles for bringing down prey...this article is interesting because it is interesting to see how T rex's relatives developed similar adaptations thru time as they went from minor to apex predators and their food source changed.
Reply | Report Abuse | Link to thisTo say T-Rex was not a scavenger is naieve at best . The function of bone crushing jaws like in the modern Hyeana is tatamount to it's survival .Once a pack drives away the killing animal they eat everything , including the bones , just like a T- Rex would have done .
Reply | Report Abuse | Link to thisAs cows in the meadows are the biggest threat to life ,or rather the end of life on our planet because of the methane they produce by farting. I tgot me thinking,if cows alone are such a threat, when we include wildebeast,antelope,deer,zebra and so on and so forth this must multiply the methane problem considerably.
Reply | Report Abuse | Link to thisMy question is, huge Dinosaurs and many of them roamed the earth for millions of years would their methane contribution perhaps been their downfall which led to their extinction.