Giganotosaurus | Coffee And Coelophysis

Unveiling Giganotosaurus: The Prehistoric Rival of Tyrannosaurus Rex

Posted on September 17, 2024 by Noelle K. Moser

email: noellemoser@charter.net

Image Credit: **Giganotosaurus** ***skeleton.*** *Fernbank Museum of Natural History in Atlanta, Georgia.*

Boasting a skull as long as a man and a body the length of a bus, Giganotosaurus is among the largest predatory theropods ever discovered. Before Tyrannosaurus Rex reigned as the King of the Dinosaurs, a larger theropods dominated the prehistoric landscape. His name Giganotosaurus Carolinii.

**Image Credit: Noelle K. Moser**. **Tyrannosaurus Rex MOR 555 and I.**

Known as the “Giant Southern Lizard”, Giganotosaurus was a formidable predator that dominated the Southern Hemisphere. This massive theropod, a member of the Carcharodontosauridae family, hunted titanosaurs and other herbivores, establishing itself as one of the largest carnivorous dinosaurs, surpassing the mighty T-rex by 2.2 tons.

Image Credit: Noelle K. Moser. Tyrannosaurus Rex MOR 555. Weight 6 tons. Length 39 ft.

Image Credit: *Comparison of the largest theropods that walked the Earth. Giganotosaurus (Green), Tyrannosaurus Rex (Blue), and Spinosaurus (Red).*

The tale of Giganotosaurus began in 1993 with the discovery of a tibia jutting from the earth in Patagonia. In 1994, paleontologists revealed the unearthing of a massive new theropod. The fossilized remains comprised a partial skull, a large portion of the vertebral column, elements of the pelvis, and fragments of limb bones.

Image Credit: ***Giganotosaurus holotype (first Giganotosaurus skeleton found) laid in the dirt.*** *Natural Science Museum at El Chocón, in the northwestern Argentine Patagonia*.

The discovery of Giganotosaurus is important because it deepened our understanding of the Carcharodontosaurid clade. Producing some of the largest theropods to ever live such as the newly discovered Meraxes Gigas, Acrocanthrosaurus, Carcharodontosaurus, and Giganotosaurus. This clade is of further interest to dinosaur enthusiasts because it allows us to explore the upper limit of theropod size.

**Image Credit:** *Noelle K. Moser.* ***Alamosaurus (Titanosaur) and Tyrannosaurus Rex. Giganotosaurus preyed upon Titanosaurs*** ***during the Cretaceous.*** *Perot Natural History Museum. Dallas, Texas.*

Nature maintains a delicate balance between predators and prey. Large herbivores require equally formidable carnivores to sustain this balance. Giganotosaurus, a giant theropod, played a crucial role in the ecosystem where it lived. The real question is not whether Giganotosaurus hunted these massive herbivores, but how it did so. This article will explore the origins of the Giganotosaurus, its hunting strategies, and ultimately why it faced extinction.

Origins of Giganotosaurus:

**Image Credit:** *Noelle K. Moser. **Giganotosaurus and I.** Knoxville Zoo. Knoxville, TN.*

During the Mesozoic, an evolutionary arms race between herbivores and carnivores ensued. As herbivores grew larger to gain a competitive advantage, the theropods also increased in size. The Jurassic period, marking the middle era of the age of dinosaurs, witnessed a remarkable diversification in dinosaur body plans. Herbivores grew larger, and thundering across the landscape were the sauropods, the giants of the Mesozoic era, including species such as Diplodocus and titanosaurs.

**Noelle K. Moser.** ***Neck of Diplodocus***. *National Museum of Natural History. Washington, D.C.*

Giganotosaurus belongs to the Carcharodontosauridae family, a group of theropod dinosaurs known for producing some of the largest carnivores ever to walk the earth. Besides their massive size, a distinctive characteristic of this group is streamlined narrow skulls with shark-like teeth.

Image Credit: **Carchardontosaurus skull.** ***The Carcharodontosauridae family possessed shark-like serrated teeth perfect for tearing the flesh off bones.***

Teeth reveal much about a creature. By examining dinosaur teeth, we can determine their diet, hunting methods, and how they consumed their prey.

During the Jurassic, the middle period of the Mesozoic Era, there was a significant increase in size among species as a result of an evolutionary arms race between predators and prey. As herbivores grew larger, carnivores also evolved to match their size.

The Jurassic saw some of the largest and most famous herbivores – the sauropods. Species such as Diplodocus, Brachiosaurus, Supersaurus, and Camarasaurus.

Image Credit: ***Comparison Graphic of some of the longest Sauropods that lived during the Jurassic***.

Counterparts to these lumbering giants, were the carnivores of the Jurassic, relatives of Giganotosaurus such as Tyrannotitan, Lusovenator, Siamraptor, and Acrocanthrosaurus.

Image Credit: An overview of the paleofauna that inhabited the Southern Hemisphere during the Mesozoic era includes theropods such as Mapusaurus (red) and Meraxes gigas (dark blue), which are carcharodontosaurs and related to Giganotosaurus.

Inhabiting the Southern Hemisphere, the relatives of Giganotosaurus, known as primitive Carcharodontosaurs, evolved into increasingly larger theropods in response to the growing size of the herbivores they preyed upon. By the end of the Jurassic and into the Early Cretaceous, the Carcharodontosauridae family comprised some of the largest carnivorous dinosaurs to have ever walked the Earth.

**Image Credit: Noelle K. Moser**. ***Life-size reconstruction of Giganotosaurus.*** *Knoxville Zoo. Knoxville, Tennessee.*

Giganotosaurus represented the culmination of an evolutionary arms race, standing as the pinnacle of the Carcharodontosauria clade.

How Giganotosaurus Hunted and Killed Prey:

Analysis of the leg bones of Giganotosaurus shows that this theropod was not built for speed, but it didn’t need to be. Although it was slower than the swift herbivores, Giganotosaurus preyed on the more ponderous sauropods, known as titanosaurs.

The titanosaurs were the last surviving group of long-necked sauropods, thriving at the time of the Chicxulub Impact at the end of the Cretaceous that ended the age of the dinosaurs. This group includes some of the largest land animals known to have ever existed, such as Argentinosaurus.

Image Credit: ***Argentinasaurus and Giganotosaurus displayed together.*** *Fernbank Museum of Natural History. Atlanta, Georgia.*

Titanosaurs lived by one rule, get big and get big fast. From the moment of hatching, sauropods like Argentinasaurus were eating machines. Dining on leaves and hard fibrous vegetation, a herd of titanosaurs could defoliate an area in a few days.

Large guts and hard-to-digest food allowed for a slow release of energy over time. This superpower aided in the ability of these sauropods to reach full size in less than ten years. Once fully grown, an adult Argentinasaurus was 128 ft long, 65 ft tall, and weighed 65 to 82 tons. This sheer size alone was enough to detour many theropods from making a meal out of these massive herbivores. Traveling in herds combined with size officially removed them from the menu.

Hunting a herd of titanosaurs was perilous. A single misstep can result in one of these colossal herbivores crushing an overzealous theropod, leading to instant death. Considering this risk, the question is not whether Giganotosaurus hunted titanosaurs, but rather how they accomplished such a feat.

Much like the enigmas posed by extinct species, the most effective way to address these questions is by examining the present. Observing lions as they hunt a herd of wildebeests, we see the predators collaborate to disperse the group, targeting the smaller, ill, or weakest members for an easier kill. A lion understands that to attack the largest, strongest, or healthiest would be, at best, a perilous endeavor. This logic can be similarly applied to Giganotosaurus.

Traveling herds exhibit remarkable organization. The young and subadults are positioned centrally, while the robust and healthy adults encircle them, forming a protective barrier. Typically, the elderly or injured members trail behind, comprising the rear guard as the herd moves across the terrain.

Understanding herd dynamics, a hunting Giganotosaurus would likely approach the herd from behind, targeting the weaker Argentinasaurus individuals. Despite not being in their prime, these titanosaurs remained formidable, capable of inflicting fatal injuries. It is probable that for these reasons, Giganotosauruses would hunt in packs, coordinating their efforts to take down one of these colossal creatures.

Evidence from the teeth of Giganotosaurus suggests that, unlike the bone-crushing bite of Tyrannosaurus Rex, Giganotosaurus had teeth better suited for slicing off flesh from its prey. Packs of Giganotosaurus would alternate in biting and slashing their prey, aiming to keep it moving and bleeding. The hunting strategy was to exhaust the prey through blood loss, fatigue, and infections caused by the theropods attacks, leading to the titanosaur’s eventual collapse under its own weight.

Trace fossils provide definitive evidence of theropod hunting strategies located along the Paluxy River near Glen Rose, Texas, USA. Here, a dramatic narrative of a dinosaur hunt is etched into the stone.

Image Credit: ***Peluxe River in Glenn Rose, Texas. Footprints from a Cretaceous hunt involving Acrocanthrosaurus and Saurposeidon recorded in stone.***

120 million years ago, on a muddy Cretaceous floodplain, the dynamics of dinosaur relationships were immortalized in stone. A herd of colossal sauropods lumbered along a waterway, stalked closely by a large carnivore. The pursuing theropod was focused, intent on the hunt.

Following behind the herd, slightly to the left, the theropod’s tracks indicate that the hunter rhythmically trailed the lumbering sauropods. Then the theropod’s footprints show that the hunter suddenly skipped a few steps, meaning only one thing, an attack.

Most of the trackway was removed. It is now preserved and displayed at The American Museum of Natural History in New York. Some of the trackway still remains submerged under the Paluxy River near Glen Rose, Texas.

Image Credit: ***Trackway from the Peluxy River on display at The American Museum of Natural History in New York***.

Giganotosaurus Extinction:

Giganotosaurus lived during the Late Cretaceous period, specifically in the Cenomanian stage, approximately 99.6 to 97 million years ago. The reasons for its extinction are not definitive, but fossil records suggest several plausible scenarios. During the latter part of the Cretaceous, environmental changes due to plate tectonics posed survival challenges for Giganotosaurus and other Carcharodontosaurids.

Additionally, around 30 million years ago, Tyrannosaurs emerged as the dominant carnivores, with Abelisaurs prevailing in the Southern Hemisphere and Tyrannosaurus Rex in the northern. It is conceivable that Giganotosaurus was outcompeted by these more adaptable theropods, leading to a gradual decline and eventual extinction.

After the extinction of the last of the Carcharodontosaurs, Giganotosaurus lost its dominance, allowing the Tyrannosaurus and the formidable Tyrannosaurus Rex to rise as the King of the Dinosaurs until 66 million years ago when the age of the dinosaurs came to an end.

I am a multi-disciplinary writer, published author and web content creator. If you like this post, visit my other sites and online writing portfolio.

The Kuntry Klucker – A Blog about Backyard Chickens.

The Introvert Cafe – A Mental Health Blog.

**Image Credit: Noelle K. Moser.** ***Me peering through the fenestra of Tyrannosaurus Rex MOR 555.*** *Cincinnati Natural History Museum. Cincinnati, Ohio.*

Resources:

Johnson-Ransom, Evan. Dinosaur World: Over 1,200 Amazing Dinosaurs, Famous Fossils, and the Latest Discoveries from the Prehistoric Era. Applesauce Press. Kennebunkport, Maine. 2023.

Keiron, Pim. Dinosaurs The Grand Tour: Everything Worth Knowing About Dinosaurs from Aardonysx to Zuniceratops. The Experiment. New York, NY. 2019.

My visit to Natural History Museums across the nation.

Theropod Evolution: Unveiling Meraxes Gigas, the Late Cretaceous Giant

Posted on December 20, 2022 by Noelle K. Moser

We have a new dinosaur! A theropod with short limbs like Tyrannosaurus Rex. Tyrannosaurus is not the only famous giant carnivorous dinosaur; meet Meraxes Gigas.

During the summer of 2022, researchers uncovered a previously unknown dinosaur from the Late Cretaceous, Meraxes Gigas. Meraxes belongs to the genus carcharodontosaurid theropods. The name, “Meraxes”, honors a dragon from the George R. R. Martin novel, A Song of Ice and Fire – Wikipedia The specific name, “Gigas”, derived from the Greek word meaning “giant”, in reference to the theropod’s large size.

Found in the Huincul Formation of Argentine Patagonia was a nearly complete skeleton. Meraxes Gigas is of pivotal importance because this discovery constitute a complete skull, partial forelimbs, complete hindlimbs, fragmentary ribs, and cervical and complete caudal vertebrae.

The hand of theropods is imperative to determine whether the specimen is primitive or derived. Primitive in dinosaur terminology means an early stage in evolutionary development. Derived means most recent in dinosaurian evolution. To help this make sense, Coelophysis is a primitive ancestor of the derived Tyrannosaurus Rex.

Image Credit: ***Gignotosaurus skeleton, notice the longer arms and three digits on each hand. Giganotosaurus is more derived than the primitive theropod Coelophysis.***

Primitive theropod dinosaurs have longer arms and digital formula I-IV. Derived theropods will have shorter arms and a reduced number of digits.

Image Credit: ***Coelophysis primitive theropod dinosaur. Notice that Ceolophysis has longer arms and 4 digits on each hand.***

Coelophysis, the oldest known theropod, defined as a primitive Late Triassic theropod had longer arms and 4 digits on each hand.

Allosaurus, more derived lived during the Middle-Late Jurassic and possess shorter arms and only three digits on each hand. Tyrannosaurus the Cretaceous apex predator had very short arms and only 2 digits on each hand.

Image Credit: Noelle K. Moser. Walter, Tyrannosaurus Rex located in Washington, D.C. has very short arms and only 2 digits on each hand.

As observed by these images, the skull, forearms, hands, and digits are gold in theropod discoveries. The hands of theropod dinosaurs tell us so much about the evolution of dinosaurs during the Mesozoic.

In addition to the forearms and digits, complete or near complete skulls found in new dinosaurs’ discoveries help us understand more about the creatures.

At first glance, the skulls of these giant theropods appear similar; massive jaws with numerous long serrated teeth. To the trained eye, the skulls of Giganotosaurus and Tyrannosaurus Rex are remarkably different.

Giganotosaurus has a long narrow skull that comes to a sharp point. The skull of Tyrannosaurus Rex is boxier and comes to a lateral line rather than a point. See the images below.

Another example of primitive and derived evolution is theropods, Allosaurus, Ceratosaurus, and, Tyrannosaurus. See the images below.

While these three theropods appear similar, Allosaurus and contemporary Ceratosaurus predate Tyrannosaurus by 80 million years.

Head Creasts:

Another feature present in theropod dinosaurs, specifically primitive species, is that of head crests. Many Late Triassic and Early Jurassic theropod species possessed head crests. It is thought that these crests were used as display features for mating and sexual dimorphism. In later derived theropod species, these crests disappear.

The image above depicts Ceratosaurus nasicornis, the apex predator of the early Jurassic, displaying crests on the head can be seen. Ceratosaurus was driven to extinction by the Late Jurassic, succeeded by the more successful Allosaurus.

Allosaurus, as mentioned above, is the most famous predecessor to Tyrannosaurus Rex. Living through the greater part of the Jurassic, Allosaurus was the apex predator of its time and possessed primitive features – three-digit hands, long forearms, and head crests. It is now known why derived theropods lose the head crests.

By the time we traverse, the expansive amount of time between Ceratosaurus and Tyrannosaurus Rex (80 million years) head crests disappear from theropod anatomy.

Size:

In addition to reduced digits and head crests, as theropods evolve they get larger. Coelophysis at maturity was about 10 feet long and weighed 100 pounds. Compare that to the Jurassic theropod Ceraosaurus which grew to 20 feet long and weighed about 2,000 pounds. Allosaurus grew to be 12 feet long and 10 feet tall weighing 2.3 metric tons. Tyrannosaurus Rex, the largest land theropod to ever live grew to 43 feet long and weighed 6-8 tons.

Meraxes Gigas:

Now, that you have a better understanding of theropod dinosaurs, let’s take another look at Meraxes gigas. Meraxes is a crucial find in the world of dinosaur studies because the remains included key anatomical features, a complete forelimb, hand, a skull, and various other bones. The most important being that of the hand and skull.

According to the research, Meraxes Gigas had tiny arms like Tyrannosaurus with three digits on each hand like Allosaurus. Tyrannosaurus and Meraxies are not related as they are separated by about 20 million years, but it does suggest that as theropods evolved larger heads, the arms shrunk, no longer useful for hunting. Regarding size, Meraxes Gigas was 36 feet long and weighed 4 tons. To put this into perspective, Meraxies is smaller than Tyrannosaurus Rex but much larger than Allosaurus. Further noted, Meraxies does not appear to have head crests.

In terms of theropod evolution, Meraxies is more derived than Allosaurus but primitive compared to Tyrannosaurus. In terms of theropod evolution, this put Meraxies Gigas living about 90 to 100 million years ago, firmly in the Late Cretaceous. Meraxes Gigas and its close relative, Giganotosaurus died out in the Late Cretaceous, succeeding their position at the top of the food chain to the tyrannosaurids, and its famous member, Tyrannosaurus Rex.

Meraxes Gigas and the newly discovered theropod dinosaur were one of the last groups of giant carnivores to walk the Earth. While we often think of Tyrannosaurus Rex as being the lone giant carnivore stalking the Cretaceous, other large theropods competed with the tyrant dinosaurs. Although Meraxes Gigas never laid witness to the meteor that would ultimately bring the reign of the dinosaurs to an end, Tyrannosaurus Rex did.

I am a multi-disciplinary writer, blogger, and web content creator. If you liked this post, chomp the subscribe button.