Top 10

Featuring tyannosaurids of the Tyrannosauridae as well as the more primitive tyrannosauroids of the Tyrannosauroidea

10‭ ‬-‭ ‬Guanlong

       As far as tyrannosaurs go,‭ ‬Guanlong is considered to be a proceratosaurid tyrannosauroid.‭ ‬In more simple terms this means that Guanlong is a basal tyrannosaur that appeared at the same time as other primitive tyrannosaurs,‭ ‬yet may not actually be a direct ancestor of the later large tyrannosaurs that were roaming around Asia and North America in the late Cretaceous.‭ ‬Never the less,‭ ‬Guanlong is still regarded as a basal tyrannosaur,‭ ‬and is a very good example of how these fearsome predators actually started out quite small.

9‭ ‬-‭ ‬Bistahieversor

       Named in‭ ‬2010‭ ‬Bistahieversor was among several tyrannosaur genera named in the early years of the twenty-first century.‭ ‬The discovery of Bistahieversor may have opened up a whole new sub-group of tyrannosaurs,‭ ‬those that lived in the southern portion of the landmass known as Laramidia.‭ ‬Back in the Cretaceous,‭ ‬the North American continent was divided into two by the Western Interior Seaway which submerged central North America all the way from Canada to Mexico,‭ ‬with the western land mass known as Laramidia,‭ ‬and the eastern Landmass known as Appalachia.
       Bistahieversor was discovered in New Mexico,‭ ‬meaning that it lived in southern Laramidia,‭ ‬a significant discovery in itself since most tyrannosaur fossils at that time had been discovered much further north,‭ ‬particularly around what is now the northern United States and southern Canada.‭ ‬An additional discovery about Bistahieversor though was that the snout,‭ ‬the portion of the skull in‭ ‬front of the eyes,‭ ‬was proportionately shorter than the known skull proportions of more northern tyrannosaurs.‭ ‬Then only one year later another tyrannosaur genus named Teratophoneus was discovered in Utah and it too had a snout that was proportionately shorter than these living further north.‭ ‬These two genera were subsequently the start of a theory that the tyrannosaurs of southern Laramidia might have been isolated from their North American cousins by rising mountain ranges and began developing along different lines.

8‭ ‬-‭ ‬Lythronax

       Another tyrannosaur named in the early twenty-first century,‭ ‬Lythronax has been credited as one of the earliest known appearances of an actual tyrannosaurid,‭ ‬with other tyrannosaurs appearing earlier in the Cretaceous being designated as more primitive tyrannosauroids.‭ ‬The Lythronax holotype was recovered from Utah,‭ ‬which means that Lythronax lived in southern Laramidia.‭ ‬Like the aforementioned Bistahieversor and Teratophoneus,‭ ‬Lythronax too had a comparatively short but deep snout.

7‭ ‬-‭ ‬Dilong

       Hailing from China,‭ ‬Dilong was a very small tyrannosaur that lived during the early Cretaceous.‭ ‬What otherwise might have been an unassuming little dinosaur still managed to shake the foundations of tyrannosaur and theropod dinosaur study,‭ ‬Dilong had feathers‭! ‬The feathers that were on Dilong were small and really more like hairs,‭ ‬and were almost certainly for the purpose of heat insulation‭ (‬though they may have also been coloured for additional display‭)‬.‭ ‬The discovery of Dilong was the catalyst to the question,‭ ‬were other tyrannosaurs feathered‭? ‬We still don’t know how to answer that question properly,‭ ‬there‭ ‬is‭ ‬evidence to suggest that they were and were not,‭ ‬and may have varied depending upon age with smaller juveniles being feathered for insulation but adults losing them because they were not necessary.‭ ‬But as we’ll see,‭ ‬it might not be that clear cut.

6‭ ‬-‭ ‬Appalachiosaurus

       Whereas‭ ‬most tyrannosaurs in North America are known from fossils in what was once the western landmass of Laramidia,‭ ‬the holotype fossils of Appalachiosaurus were actually discovered in the eastern landmass of Appalachia,‭ ‬leading to the name Appalachiosaurus which translates to English as‭ ‘‬Appalachian lizard‭’‬.‭ ‬The discovery of Appalachiosaurus has revealed that tyrannosaurs were probably roaming across both sides of North America during the Cretaceous.‭ ‬The holotype specimen of Appalachiosaurus was found to have a tooth from the giant crocodile Deinosuchus stuck in one its tail vertebrae.

5‭ ‬-‭ ‬Eotyrannus

       For the best part of a century the tyrannosaurs were popularly regarded as large predatory dinosaurs that hunted in what we now call eastern Asia and North America.‭ ‬What makes Eotyrannus different is that it didn’t live in Asia or North America,‭ ‬the holotype fossils of this genus were discovered in England‭! ‬Not only does this make Eotyrannus the first tyrannosaur genus to be discovered in the British Isles,‭ ‬but the first tyrannosaur to be discovered on the European continent.‭ ‬The holotype fossils of Eotyrannus indicate an individual that was about four meters long,‭ ‬but this individual was also a juvenile,‭ ‬and fully grown adults would have certainly been larger,‭ ‬though exactly how much larger is difficult to say without a second,‭ ‬ideally adult specimen.‭ ‬Being larger than four meters would be just as well however as the carcharodontosaur Neovenator and the spinosaur Baryonyx are both known from the same fossil formation as Eotyrannus,‭ ‬and both of these are known to have been much larger than the holotype individual.

4‭ ‬-‭ ‬Albertosaurus

       Albertosaurus is one of the more famous tyrannosaur genera from North America,‭ ‬and one of the last known to live at the end of the Cretaceous before the dinosaurs died out.‭ ‬With the largest individuals reaching sizes of ten meters long,‭ ‬Albertosaurus had a relatively gracile‭ (‬light‭) ‬build for a tyrannosaur and was similar to the genus Gorgosaurus‭ (‬which some palaeontologists consider to be the same genus as Albertosaurus,‭ ‬though others insist that they were different‭)‬.
       The main controversy concerning Albertosaurus is the theory about if they were pack hunters,‭ ‬a theory stemming from the Dry Island bonebed.‭ ‬Situated near the Red Deer River in Alberta,‭ ‬Canada,‭ ‬the bonebed was first discovered in‭ ‬1910‭ ‬by the famous American palaeontologist Barnum Brown,‭ ‬yet was surprisingly forgotten about until it was re-discovered in‭ ‬1997‭ ‬by an expedition from the Royal Tyrrell Museum of Palaeontology.‭ ‬This bone bed has the remains of at least twelve,‭ ‬but possibly as many as twenty-six Albertosaurus individuals.‭ ‬In addition to this great number,‭ ‬the individuals range from very small juveniles,‭ ‬to very large ten meter long adults.
       There are many ways that such a bonebed could be read but the accumulation of such a large concentration of all the same dinosaur and not anything else does suggest that this is bonebed is not the result of a random placement.‭ ‬If it represents the remains of a family pack is controversial and certainly not certain,‭ ‬but other large theropod groupings have since been found though certainly not yet in such numbers as the Albertosaurus bone bed.

3‭ ‬-‭ ‬Tarbosaurus

       With the exception of Alectrosaurus,‭ ‬the tyrannosaurs were regarded as primarily North American dinosaurs for the first half of the‭ ‬20th century,‭ ‬then in‭ ‬1955‭ ‬things changed with the description of Tarbosaurus.‭ ‬The problem with Alectrosaurus was that it was only named from very partial fossil material that had been perceived to be similar to Gorgosaurus from North America,‭ ‬but further details were impossible.‭ ‬The Tarbosaurus holotype however was much more complete,‭ ‬so much so that when it was first named it was described as a species of Tyrannosaurus,‭ ‬Tyrannosaurus bataar.‭
       It was not long before the specimen was renamed Tarbosaurus,‭ ‬but the debate about whether Tarbosaurus should be a distinct genus or a species of Tyrannosaurus has been ongoing ever since as the differences between them are only slight.‭ ‬Most modern thinking however seems to support keeping Tarbosaurus as a distinct genus,‭ ‬and studies associated with the aforementioned Lythronax above suggest that the Asian tyrannosaurs are of‭ ‬a‭ ‬group that are distinct‭ (‬but still related‭) ‬to the North American tyrannosaurs.
       Tarbosaurus is so far known mostly from Mongolia,‭ ‬with some remains from China.‭ ‬The genus Alioramus which is also known from Mongolia,‭ ‬was once considered to be a juvenile Tarbosaurus,‭ ‬but new specimens of this dinosaur prove that it is a distinct genus from Tarbosaurus,‭ ‬though one that was closely related to it.

2‭ ‬-‭ ‬Yutyrannus

       When Dilong was found it led to speculation that smaller tyrannosaurs and juveniles of larger ones probably had feathers.‭ ‬Then in‭ ‬2012‭ ‬three individuals of a new tyrannosaur genus were found in Aptian aged rock in China.‭ ‬All three of these tyrannosaurs had feathers,‭ ‬and the largest individual was up to nine meters long‭! ‬The idea that only small tyrannosaurs had feathers is now out of the proverbial window,‭ ‬but Yutyrannus may be an exception not the rule.
       Analysis of the fossil site‭ ‬suggests‭ ‬that Yutyrannus came from a colder climate and thus necessitated the need for feather insulation when fully grown.‭ ‬By comparison the limited known skin impressions of tyrannosaurs from North American indicate that at the time of death these individuals had bare skin,‭ ‬and not an extensive covering of feathers like Yutyrannus.‭ ‬It could be because the North American tyrannosaurs were living in a warmer climate,‭ ‬or perhaps after many more millions of years of evolution they lost their feathers,‭ ‬or perhaps even developed medical conditions that caused feather loss which then partly resulted in their deaths.‭ ‬What is known for certain is that when Yutyrannus was described it gained the title of largest known feathered dinosaur,‭ ‬comfortably beating the previous record holder,‭ ‬a therizinosaur named Beipiaosaurus.
       The description of feathers upon such a large dinosaur can easily overshadow the overall significance of a discovery.‭ ‬When Yutyrannus was found,‭ ‬it was three individuals,‭ ‬all of different ages that were found together.‭ ‬Like with Albertosaurus,‭ ‬this raises the question,‭ ‬did Yutyrannus hunt in packs‭? ‬Perhaps as a small family unit‭?

1‭ ‬-‭ ‬Tyrannosaurus

       What else could it be‭? ‬Tyrannosaurus has been by far the most popular dinosaur ever since it was introduced to public in the early‭ ‬20th century,‭ ‬and since this time whenever a film,‭ ‬book or video game needs a dinosaur for a primary antagonist,‭ ‬nine times out of ten it will be a Tyrannosaurus.
       Partly because of the popularity,‭ ‬Tyrannosaurus has had to put up with a lot bad publicity with a lot of people accusing it of only being an‭ ‘‬obligate scavenger‭’‬,‭ ‬despite the fact that many of the arguments that claim to‭ '‬prove‭’ ‬this can easily be dismissed as nonsense.‭ ‬This is not to say that Tyrannosaurus never scavenged carcasses,‭ ‬it would be very strange if Tyrannosaurus didn’t because scavenging is actually normal behaviour for all meat eating animals.‭ ‬But taking advantage of the occasional‭ '‬free meal‭’ ‬is very different from only scavenging and never hunting.‭
       For the best part of a century Tyrannosaurus was regarded as the largest known theropod dinosaur,‭ ‬and it was not until later in the twentieth century that Tyrannosaurus lost this title.‭ ‬Tyrannosaurus is still‭ ‬comparable to the largest theropods,‭ ‬and as of‭ ‬2014‭ ‬is still the largest known tyrannosaur.‭ ‬Tyrannosaurus is also regarded as having potentially the most powerful bite of not just any dinosaur,‭ ‬but also any known land animal of all time.‭ ‬This is thanks largely to the size and width of the skull which allows for larger jaw closing muscles.‭ ‬In addition to that,‭ ‬the skull width and eye placement would have allowed for visual ability far surpassing that of any human,‭ ‬and even birds of prey like eagles which are regarded as having some of the best eyesight in the known animal kingdom.


Random favourites