The Giganotosaurus existed during the Turonian stage of the late cretaceous period about 90 million years ago. It was first discovered in 1995 in the Argentinean region of Patagonia at the Rio Limay Formation by Ruben Carolini. The meaning of the name stems from the Greek word ‘gigas’ meaning giant, ‘notos’ referring to the south and the term ‘saurus’ meaning lizard, giving us the ‘giant southern lizard’

As its name suggests the Giganotosaurus is considered by scientists to be the largest of the terrestrial carnivorous dinosaurs, even larger than the ferocious predator Tyrannosaurus Rex.

Taxonomy

The Giganotosaurus was a member of the Carcharodauntosaurid dinosaurs who were a group of ultra large theropod dinosaurs. The Carcharodauntosaurid family contained some of the largest carnivorous predators of all time, apart from the Giganotosaurus other members included the Mapusaurus, Carcharodontosaurus, and the Tyrannotitan. The family to surpass the Carcharodauntosaurids in size were the Spinosaurids.

Physical Features

The Giganotosaurus was a mammoth sized carnivore which measured around 45 ft in length and weighed a little over 6 tonnes, surpassing the T. Rex by a small margin. Like most Theropods the Giganotosaurus had a prominently visible and large head and is believed to have possessed the longest skull among the various theropod dinosaurs.

With such a large skull there was space for a very well developed olfactory region suggesting an extremely sharp sense of smell. However it’s worth mentioning at this point that skull size isn’t everything, as despite the Giganotosaurus having a larger skull its brain was almost half the size of the Tyrannosaurus.

Now compared to the T. Rex whose teeth were ideal at snapping and cutting through bone, the Giganotosaurus had much smaller, narrower and more evenly sized teeth. This would have made them ideal for slicing flesh and leaving deep cuts in their victims as opposed to the bone crushing effect that the T. Rex had.

Behavioral Patterns & Hunting

Thanks to its size, scientists believe the Giganotorsaurs was more than capable of going after the super sized herbivores such as the Argentinosaurus and the Titanosaurus. In fact Titanosaur fossils were found extremely close to those of the Giganotosaurus making this an even higher possibility.

In terms of hunting style unlike the Tyrannosaurus who was a solitary hunter scientists believe the Giganotosaurus may well have been a pack hunter. The reason for this stems from the study of the other Carcharodauntosaurid dinosaurs whose fossils were often discovered in groups, indicating a collective hunting or herd like grouping. With the Giganotosaurus this is even more likely as going after the super sized herbivore giants would have been no easy task on ones own, but as a pack it may well have worked quite well.

The Tyrannosaurus or T. Rex existed in the late cretaceous period some 65 million years ago. A carnivorous dinosaur and an extremely popular icon in todays movie culture this dinosaur is probably one of the most talked and read about dinosaurs ever to have existed. With some amazing scenes in both Jurassic Park and the recent King Kong movie it’s no wonder he’s so popular.

The name Tyrannosaurus Rex means ‘Tyrant Lizard King’ which stems from the Greek word ‘tyranno’ meaning tyrant, ‘saurus’ meaning lizard and ‘rex’ meaning king. The grand name comes directly from the fact that the T. Rex was most probably one of the largest and most terrifying carnivores of its time.

Taxonomy

The Tyrannosaurus a bipedal theropod was a part of the Tyrannosaurid family which existed in most parts of western north America as well as some parts of Asia. For a long time it was believed that the T. Rex was the largest carnivorous dinosaur of them all, but that was before the Giganotosaurus and Carcharodontosaurus were discovered.

Despite not being the largest of the carnivores it was still the largest member of the Tyrannosaurid family and of course recognised as one of the fiercest land predators ever to exist. Over time scientists have classified and re-classified discoveries in and out of this group as quite clearly the tyrannosaurid group is a bench mark in its own right.

As an example in 1955 Russian paleontologist Evgeny Maleev named a new species called Tyrannosaurus bataar which was discovered in Mongolia. By 1965 this species had been regrouped adn renamed to Tarbosaurus bataar. Despite the renaming it’s still thought of being a close sister and asian version of the Tyrannosaurus rex.

Physical Appearance

At over 20 ft tall, 40 ft long and weighing up to 8 tonnes the Tyrannosaurus was longer than the width of a tennis court, heavier than an african bull elephant and tall enough to look into an upstairs window. It’s massive legs bore its weight on three large, bird like clawed toes, whilst its arms which despite being extremely short were strong and powerful with 2 clawed digits.

Large Skull

One feature that stood out in all Tyrannosaurids was the size of their skull. In simple words it was huge and at 5ft long the skull was almost half as long as the backbone between the hips and the head. The head was basically the size of a small car and considered huge even for dinosaurs.

To support such a large head the T. Rex had an extremely short but muscular neck giving it extra strength and allowing it to stabilise the head as it moved. Obviously a huge skull meant plenty of room for large teeth which were so hard that they were known to penetrate even bone.

All these characteristics meant that the Tyrannosaurus Rex had one the strongest bite forces of any dinosaur that ever existed. The pressure exerted in a single bite was equivalent to around 4 tonnes per square inch. Obviously with such a mean bite teeth are bound to be lost which luckily for the T. Rex and the rest of the tyrannosaurid family grew back throughout its life.

Vision & Smell

The T. Rex had a small brain in proportion to its body, but even so it was larger than most other dinosaurs. Its eyes were positioned on the front of the skull which is very similar to the way human eyes are positioned, and would have meant its ability to focus and judge distance objects was very good.

Scientists also believe that a large portion of the brain was allocated to smelling making the T. Rex a very strong sniffer. If you combine the strength of the eyes with the strong sense of smell you very quickly appreciate how these two natural abilities would have made the Tyrannosaurus a very effective predator.

The Tail

As well as a large head the Tyrannosaurus also possessed an equally large and stiff tail. Most scientists believed the weight of the tail would have meant it dragged on the floor as it moved, however more recent studies challenged this stating that the tails weight formed a counter balance to the extremely heavy head. If this were the case then it would actually be carried in the air to counter the heavy head which would have been in a forward leaning position.

Tiny Arms

Despite having arms that were only 2-3 ft long they were still however extremely muscular and able to support hundreds of pounds of weight.

So what were these arms used for ? Well a number of theories are plausible and one of them is that the arms were used to assist the T. Rex whilst lifting itself off the floor. Others say that the two sharp claws on each arm were used to hold its prey whilst it devoured them with its mouth.

A Quick Size Comparison

When we start to talk about the Tyrannosaurus and its huge head it’s very easy to forget what it’s overall size was in comparison to the long necked sauropod herbivores. Some examples include the Sauroposeidon which is the tallest known dinosaur and stood at 55 ft (17 metres) in height, the T-Rex as you can see was almost a third of its height.

In fact there were even larger sauropods such as the Argentinasaurus who was 115 ft long (35 metres) and weighing between 80-100 tonnes. Compare that to the T. Rex which was only 6-8 tonnes and 40 ft in length and you quickly realise the size difference. We throw this section in because most readers get so amazed with the grandness and power of the T. Rex that they often forget his overall size in comparison with the rest of the dinosaurs.

T-Rex Top Speed

The Tyrannosaurus Rex had one of the strongest not to mention longest legs of any Theropod. These massive legs combined with three huge toes on each foot meant the T. Rex was able to take very long strides covering distances of up to 15 ft with each step, thus giving it a top speed of around 25 mph.

Behavioral Patterns & Hunting

It’s thought that the T. Rex probably lived close to its prey which were in most cases plant eating herbivores. This would imply that its primary dwelling would have been near forests, open woodland, rivers and valleys rich in plant life.

We know the T. Rex was probably well suited to hunting but how it hunted is an issue up for debate. Most scientists feel that due to the lack of fossil evidence suggesting group hunting, it was most likely a solitary hunter.

How it fared against other dinosaurs who did hunt and exist in packs is an interesting question. Some have said the T. Rex possessed such a powerful bite that this alone would have been a huge deterrant and factor in maintaining its superiority over other large dinosaurs and pack hunters.

It’s absolutely certain that the Tyrannosaurus would have eaten large dinosaurs if they were already dead but may also have attacked animals that were either too young, sick or old to protect themselves. Some scientists believe this behaviour is scavenger like whilst others feel it’s just a fact of life.

T. Rex Prey

In terms of what and who it preyed upon, there’s fossil evidence to suggest it commonly consumed both Triceratops and the duck-billed Hadrosaurs such as the Corythosaurus. In most cases scientists feel that an initial power bite would have severely crippled its prey causing massive blood loss. This would eventually cause its prey to lose strength and even collapse. At this point the T. Rex could quickly use both its foot claws and mouth to finish off its opponent.

Fossils

In total around 30 Tyrannosaurus Rex fossils have been recovered with the first T. Rex fossil being discovered in 1902 by Barnum Brown in South Eastern Montana, USA. Most other T-Rex fossils were also found in this region but some have also been found in Canada and parts of Asia such as Mongolia.

The Coelophysis was a small carnivorous dinosaur whose existance dates back to the Triassic period over 228 million years ago. It owes its name to the Greek root word “Koilos” which refers to something hollow while “Physis” simply refers to a form or structure. Their name emphasises their light and hollow bone structure.

The very first specimens of the Coelophysis were first discovered in 1881 by David Baldwin and was quickly named C. Baur. However these fossil samples were not enough to give scholars any real data on this new dinosaur species.

While researchers continued to work, it was in 1947 that a huge grave of Coelophysis fossils were unearthed in the Ghost Ranch in New Mexico. Not only was this a great find but it was the first time such a huge collection of dinosaur fossils had been excavated in one go. Finds like this usually presume that these dinosaurs were swept away as a result of some natural hazard like a flash flood and buried instantly.

Taxonomy

The Coelophysis was initially considered to belong to a single species, that of the C. Bauri. However, there are two other kinds which have been recently added as a variant of this type, namely the C. willistoni and C. longicollis which are known to have no other similarities except that they all belong to a similar genetic structure.

Physical Features

The Coelophysis was a slim theropod which was probably as long as a car but as light as a 7 year old. They were one of the earliest dinosaur species and despite only being 2-3 meters in length were vicious pack hunters.

There light weight and hollow bone structure was a big deal and despite being a theropod, their early existance meant they carried several features which were considered to be the first of a kind in dinosaurs. Other features such as having 4 digits on each hand as opposed to 3 offers a great example of features which were later lost by theropods.

These early dinosaurs had a long head, an elongated snout and a noticably long curvy neck. Add to this extremely slender limbs and this reptile almost resmbled a bird. However unlike birds the Coelophysis had teeth, clawed hands and a long bony tail.

Swift Commuters

The most interesting section of the body was probably their vertebra which were arranged in such a way that they prevented the long tail from constantly moving up and down. This combined with their super light weight may have contributed to their ability to commute swiftly.

Behavioral & Hunting Patterns

Most of the information regarding the life and times of the Coelophysis was obtained from the fossil specimens that have been discovered from the Ghost Ranch in New Mexico. As stated before the Coelophysis were meat eaters and probably hunted other small lizards and small mammals.

Not dissimilar to scavengers, they probably hunted in packs and pounced on their prey digging their edged and jagged teeth into their prey. Their teeth were extremely sharp on both edges and therefore easily pierced unarmored skin. Like most hunters the Coelophysis probably lost and regrew its teeth throughout its lifetime.

Cannibalistic Or Not ?

Severeal researchers have also pointed that in their initial stages the Coelophysis may have displayed cannibalistic traits. This claim was originally supported by various studies of the abdominal cavity of certain fossil specimens which revealed the presence of other Coelophysis samples. Whether this is 100% accurate or not is debatable as other scientists believe those specimens were in actual fact Crutotarsan reptiles.

The Allosaurus a member of the Allosaurid family was first discovered during the closing years of the 19th century by Othniel Charles Marsh in 1877. It existed in the late Jurassic period about 150 million years ago and almost all of it’s fossils have been in the Morrison Formation in the North America, as well as in Portugal and Tanzania. The name Allosaurus means “different lizard” and is derived from the Greek root word “allos” meaning “different”.

Taxonomy

Like most dinosaurs the Allosaurus is believed to have had many variations of it’s kind. Scientists have thus far classified about seven dominant kinds of which some of the prominent types include Allosaurus Fragilis, Allosaurus Atrox, Allosaurus Maximus, Allosaurus Amplexus.

Physical Features

In terms of physical structure, the allosaurus like most theropods was of a high stature. It’s believed to have grown to about 30ft tall, and being almost 40ft in length. Like the T-rex the most striking feature had to be the size of it’s skull which was enormous compared to the size of it’s much shorter neck. Again like the Tyrannosaurus the Allosaurus possessed a huge tail (acted as a counter balance) and tiny forelimbs consisting of three fingers. It’s estimated weight was around 2.3 metric tons.

Skull & Teeth

The skull of the Allosaurus was estimated to be around 33 inches in length giving it a decent sized jaw size. Each premaxilla (the bones forming the tip of the snout) held five teeth and each maxilla (the bones in the upper jaw) and dentary (the bones of the lower jaw) had around 14 to 17 teeth giving the Allosaurus plenty of teeth for the size of it’s skull.

The teeth became shorter, narrower and more curved as you went towards the back of the skull and were probably constantly replaced during it’s lifetime. It’s no wonder that teeth comprised a significant proportion of the excavated remains of any Allosaurus.

Some other interesting features about the Allosaurus include the presence of 2 horns which sat above and in front of the eyes and the fact that it had some of the best developed sinuses and smelling abilities of the theropods.

Behavioral Patterns & Hunting

Scientists have been united in the fact that the Allosaurus was a voracious predator and one of the most feared marauders amongst the dinosaurs. Their preferred victims were herbivorous (plant eating) dinosaurs like the Sauropods, Ornithopods and the Stegosaurids.

Out of the above, it’s thought that the Sauropods were probably their most favoured food item, due to the extensive presence of Sauropod remains on the teeth of Allosaurus fossils. In the case of Sauropods studies have shown that the Allosaurus probably tore the flesh off from living Sauropods deferring the kill of its prey for some time.

In terms of hunting behaviour it’s believed that the Allosaurus usually hunted in groups and their huge tail was also a vital component in aiding the trapping of other dinosaur variants as prey. This hunting in groups is attributed as a unique feature in the Allosaurus as it has been observed that most vertebrates do not usually hunt in groups.

This carnivorous dinosaur was also extremely protective about its young, often hunting and gathering food for them till they were fully grown and capable of looking after themselves.

Anti Social

The Allosaurus, like most Theropods were not very social and are believed to have been exceptionally reserved. This meant that even interactions with other dinosaurs of their own kind were met with distaste. Some scientists believe that the Allosaurus often wounded members of it’s own clan if any miscommunication or misunderstanding happened. The results of these interactions could often be fatal.

Several scientists believe that the Allosaurus may even have scavenged off the remains of other dead or immobilized Allosaurus dinosaurs.

Allosaurus Young

One of the key differences between the adult and child Allosaur was the huge difference in hind limb length. The hind limbs of a child allosaurus were often considerably longer than the adults which allowed them to move swiftly and catch much smaller and faster types of prey. This would suggest that as the Allosaurus matured it would start hunting larger and stronger prey as it would be incapable of capturing the faster dinosaurs that it might have hunted when younger.