Extinction | Coffee And Coelophysis

Stan the T-Rex: History and Mystery of a Fossil Star

**Image credit**: *Mary Haggard*. ***BHI 3033 “Stan” and I in a quiet reverent exchange separated by millions of years but connected by curiosity.*** Houston Museum of Natural Science

Since the first Tyrannosaurus Rex specimen was discovered in 1902, this theropod has captured the human imagination worldwide. Despite the popular belief that Tyrannosaurus Rex is a homogenous species, each of the 50 Tyrannosaurus Rex specimens displayed in museums worldwide represents unique individuals.

Image Credit: Noelle K. Moser. Tyrannosaurus Rex MOR 555 (Walter) and Triceratops. National Natural History Museum. Washington, D.C.

Tyrannosaurus Rex is the most popular but least understood dinosaur of the Mesozoic. The war still rages on whether T-rex was an opportunistic scavenger or the cold blooded butcher of the Cretaceous. While no carnivore would pass up a free meal, the teeth suggest that the T-rex could kill and consume meals whole with bone-crunching force. Mischaracterized as a mindless brute solely focus on killing, this intelligent animal was social and possessed the complex capability to live in social groups.

**Image Credit:** *Noelle K. Moser.* Me peering through the fenestrae of Tyrannosaurus Rex MOR 555. The serrated conical teeth of Tyrannosaurus Rex were the most extreme anti-tank weapon nature produced. Capable of piercing the armor of any horned or armored dinosaurs during that Cretaceous. Cincinnati Museum Center. Cincinnati, OH.

Furthermore, some studies suggest that Tyrannosaurus rex may have been more than just a fearsome predator—it could have also been a devoted partner. Take Sue, one of the most iconic T. rex specimens: her skeleton is marked with numerous injuries, some quite severe, yet evidence of calcium deposits indicates significant healing. While Sue’s survival likely speaks to her own resilience, comparisons with modern birds—T. rex’s closest living relatives—raise the possibility that she may have been tended to by a loyal companion during recovery.

***Tyrannosaurus Rex, Sue.*** *Noelle K. Moser*. *Chicago Field Museum.*

Despite all we’ve uncovered about the iconic Tyrannosaurus rex, much about this formidable predator remains shrouded in mystery. With each new discovery, we gain deeper insight into its biology and behavior. Stan, in particular, gave us an unprecedented look at what may be evolution’s most advanced anti-tank weapon—a predator equipped with bone-crushing strength and armor-piercing teeth capable of breaching even the most well-defended dinosaurs.

**Image Credit:** *Noelle K. Moser*. **A cast of BHI 3033 (Stan) and I. The largest T-rex fossil discovered with a nearly complete skull, offering an unparalleled glimpse into the brain structure of the Tyrannosaurus Rex.** Perot Natural History Museum. Dallas, Texas.

Contrary to the long-held image of Tyrannosaurus rex as a solitary predator that only sought out others to mate, recent research paints a far more social picture. Rather than roaming alone through the Late Cretaceous landscape, T. rex may have hunted in coordinated groups. If a single T. rex lurking in the underbrush is terrifying, imagine a pack working together to ambush their prey. The idea of these apex predators operating as a unit is enough to send shivers down the spine of anything unfortunate enough to cross their path.

Studies on Stan and other robust Tyrannosaurus Rex fossils, suggest that the T-rex’s intelligence was among the highest, akin to that of Deinonychus (Velociraptor) in terms of social intelligence, enabling them to cooperate in packs for hunting and nurturing their young.

This massive and intimidating theropod, renowned for its bone-shattering bite, was both highly social and remarkably intelligent. Today, the mighty Tyrannosaurus Rex is recognized as a cunning and formidable predator, rightfully earning its crown as the undisputed King of the Dinosaurs.

Each Tyrannosaurus Rex tells a unique story captured in stone. Their bones whisper tales of thrilling lives, injuries, illness, dramatic and sometimes violent deaths, each different from the next. This article embarks on an exciting journey into the world of the Tyrannosaurus Rex, featuring the fascinating story of one of its most famous fossils, BHI 3033, also known as Stan.

The Story of Stan:

**Image Credit**: *Noelle K. Moser*. ***Stan, standing at the intercetion of science and popular culture.*** Houston Museum of Natural Science.

In 1987, deep beneath the K–T boundary in the Hell Creek Formation near Buffalo, Harding County, South Dakota, a remarkable discovery waited in silence—16 meters underground, laid Stan, entombed for 66 million years. Excavation of his fossil began on April 14, 1992, led by the Black Hills Institute, and was completed by May 7 of the same year. Cataloged as BHI 3033, the specimen was named “Stan” in honor of its discoverer.

After more than 30,000 hours of detailed preparation, Stan made his public debut in June 1996. His first appearance was on an international tour in Japan, captivating audiences across the globe. Today, Stan remains one of the most complete Tyrannosaurus rex skeletons ever unearthed, providing an extraordinary window into the anatomy and behavior of this iconic predator.

Life in Hell Creek During Stan’s Life:

*AI image of representing Stan in Late Cretaceous Hell Creek.* **Powered by Open AI.**

Life in the Hell Creek Formation during the Late Cretaceous—around 66 million years ago—was vibrant, dynamic, and full of drama. It was a lush, subtropical environment with a warm, humid climate, lots of rainfall, and diverse ecosystems including coastal plains, swamps, rivers, and forests. Very silmilar to the bayous of Louisiana and the Pacific Northwest today.

Living along side Stan were a variety of paleoflora and paleofauna. Some of the most recognizable dinosaurs shared this ecosystem.

Triceratops – Herd-dwelling horned dinosaurs, likely locking horns over mates or territory.

Edmontosaurus – Large, duck-billed hadrosaurs, probably migrating in herds and grazing like prehistoric cattle.

Ankylosaurs and pachycephalosaurs – Armored tanks and dome-headed headbutters roaming under the cover of trees.

Small theropods like Troodon and Dromaeosaurus – Agile predators or opportunistic omnivores.

Other Life Living In Hell Creek with Stan:

Crocodilians like Borealosuchus – Lurking in the water, ambushing anything that got too close.

Turtles, amphibians, and early mammals – Filling ecological niches on the ground, in trees, and even underground.

Pterosaurs – Soaring above the forests, especially near waterways.

Birds – Already fairly modern in form, flitting through the canopy or diving for fish.

Paleofauna of Hell Creek:

Image Credit: **Noelle K. Moser**. ***Paleofauna of the Cretacious were ferns and flowering plants***. National Botanical Gardens. Washington, D.C.

The paleoflora of the Hell Creek Formation during the Late Cretaceous was incredibly rich and diverse. It reflected a humid, subtropical to warm temperate climate, with a strong influence from nearby coastlines and river systems. The vegetation was a mix of ancient holdovers and newer, flowering plants, painting a picture of a world in ecological transition.

Recognizable and common plants thriving in Late Cretaceous Hell Creek.

Angiosperms (Flowering Plants)

Platanaceae (sycamore relatives)

Magnoliaceae (magnolia-like plants)

Lauraceae (laurel family)

Fagaceae (beech/oak relatives)

Conifers (relatives of evergreen trees)

Ferns and Tree Ferns

Mosses and Liverworts

The vegetation of Hell Creek supported a complex web. These plants also helped form the distinctive layered stratigraphy of Hell Creek, especially with leaf litter, root systems, and decaying wood contributing to the fossil record.

**AI generated Image**. *Paleoflora of Hell Creek during the Cretaceous.* **Powered by Open AI.**

The audio landscape of Hell Creek was vibrant and diverse. The buzz of large insects, chirps, and dinosaur calls echoing across the floodplains, and maybe the distant rumble of a thunderstorm rolling in from the coast. Life was beautiful and brutal.

Daily Life In Late Cretaceous Hell Creek:

Using our minds eye and evidence from the fossil record, we can construct a plausable scenario from Stan’s perspective in Late Cretaceous Hell Creek.

Let’s drop into a moment in Hell Creek—quiet, moody, and full of tension just under the surface.

AI image of Stan, Late Cretaceous Hell Creek. **Powered by Open AI.**

It’s early morning. A pale sun pushes through low clouds, casting a gauzy light across the misty floodplain. The air is heavy with moisture, thick with the scent of wet ferns, rich soil, and the musk of animals you can’t yet see. Somewhere in the distance, a chorus of frogs sings its final notes before the heat rises. A breeze rustles the leaves of broad-leaved magnolias and ginkgoes, sending tiny droplets scattering from the canopy like diamonds.

You’re standing at the edge of a slow-moving river, its banks muddied by last night’s rainfall. A snapping turtle eyes you warily before vanishing beneath the surface with barely a ripple. Dragonflies hover above the reeds like flickering ghosts, their wings catching light that breaks through the trees.

Suddenly, the brush on the other side of the water shifts. A young Edmontosaurus steps out, its nostrils flaring, scenting the air. Its massive, pebbly hide is dappled with dew and the shadow of leaves. It cranes its neck, listening, before lowering its head to drink.

Then—a silence. Not peaceful, but alert. A flock of early birds bursts from the trees with a shriek. The Edmontosaurus jerks upright, trembling. Across the clearing, between two tree trunks as wide as a truck, a shape stirs.

Out steps Stan. Not charging. Just there. Quiet. Intent. His skin is mottled, mud-streaked, speckled with insects and scars from battles with other tyrannosaurs in the area. Each footfall is heavy but controlled, barely making a sound on the damp earth. His eyes are fixed on the hadrosaur—not wild with hunger, but cold and assessing.

The Edmontosaurus bolts.

In a flash of spray and crashing reeds, Stan lunges after it, jaws parted just enough to reveal evolution’s most advanced anti-tank weapon—a predator equipped with bone-crushing strength and armor-piercing teeth capable of breaching even the most well-defended dinosaurs. The trees shudder with the pursuit. A burst of birds takes flight, and somewhere in the distance, an unseen Triceratops bellows like thunder.

Then, silence again. The floodplain breathes.

Hell Creek wasn’t just a jungle full of dinosaurs—it was also the scene of an impending catastrophe. The ecosystem was thriving but balanced on a knife’s edge, and just before the asteroid impact, you’d never know extinction was looming.

**AI generated image:** *While the conditions of Stan’s death are unclear, life in Hell Creek came to an abrupt end when with Chicxulub impact.* **Powered by Open AI.**

What Remained of a Fossil Star?

It is unclear how Stan died. Based on the preservation of his skeleton, Stan died near a water source as his body was fossilized relatively quickly with minimal signs of scavenging by ofher animals living in Hell Creek at his death.

“The Hell Creek Formation during the Late Cretaceous represented a fluvially dominated floodplain system. The high water table and frequent sedimentation events within this environment facilitated exceptional fossil preservation, as evidenced by specimens such as Tyrannosaurus rex individuals Stan and Sue.” (Johnson, Nichols, Hartman. 2002).

**Image Credit**: *Mary Haggard*. ***Stan and I. The remains of a fossil star***. Houston Museum of Natural Science.

The cometeness of Stan’s skeleton totalled 190 bones, or 63% of the skeleton by bone. (Larson, 2008).

Preserved skeletal elements of Stan include:

A nearly complete skull,

59 vertebrae (9 cervical, 14 dorsal, 5 sacral, 31 caudal);

24 cheverons;

14 cervical ribs;

12 dorsal ribs;

Anearly complete pelvis;

Left femora (femor or thigh bone);

Both tibiae;

Both calcanea;

Astragali;

Left metatarsals; and

11 pes phalanges.

**Image Credit:** *Noelle K. Moser*. ***Cast of Stan***. *Peroit Natural History Museum. Dallas, TX.*

The prehistoric story preserved in Stan’s bones:

**Image Credit:** *Noelle K. Moser*. ***BHI 3033, Stan, large jaws slightly agape, Stan embodies the powerful presence one of the most iconic creatures that evolution ever produced.*** Houston Museum of Natural Science.

Stan’s fossil tells a compelling story of adversity, injury, determination, and survival. Among the most striking findings is the presence of fused cervical vertebrae, which clearly indicates that at some point in his life, he was bitten by another T-rex.

The fossil record demonstrates that tyrannosaurs engaged in face biting, a well-documented ritualistic behavior in the fierce competition for mating rights. The calcium deposits found in Stan’s bones confirm that he not only survived this injury but healed from it. However, the fused vertebrae likely caused him discomfort for the rest of his life, underscoring his resilience and tenacity in the face of challenges.

**Image Credit:** *Mary K. Haggard.* ***The fusing of Stans 5-6 Cervical Vertebrae indicates that at one point in his life he was bitten by another Tyrannosaurus Rex***. Houston Museum of Natural Science.

The Cretaceous period posed significant challenges for the Tyrannosaurus Rex. As the undisputed King of the Dinosaurs, T-rex had its advantages, but it was not immune to the hidden dangers of Mesozoic life. Just like today, parasites were a prevalent issue for dinosaurs, and Stan was no exception. Bone infections caused by Trichomonas protozoan—common parasites found in both birds and dinosaurs—were evident, marked by distinct round holes on the jaws of several T-rex specimens. These infections led to inflammation and pain, which undoubtedly affected their hunting and feeding efficiency.

**Image Credit.** *Noelle K. Moser*. ***Round holes on the side of Stan’s lower jaw show indications of bone infection caused by bone eating parasites.*** Houston Museum of Natural Science.

Most Complete Tyrannosaurus Rex Skull

Stan’s fossil has yielded valuable insights into the intricate structure of a Tyrannosaurus rex skull. Exceptionally well-preserved, it has enabled scientists to create a brain cast from the brain case associated with this specimen. Much like in humans, the brain leaves distinct impressions on the interior of the skull, allowing for a detailed examination of its anatomy.

Studies of these brain casts indicate that the T. rex possessed a notably large auditory lobe, particularly attuned to low-frequency sounds below 40 Hz. This finding not only suggests that Tyrannosaurus rex could hear such low sounds but also raises the possibility that it could produce them. While humans are unable to perceive sounds below 20 Hz, one would likely be able to sense the vibrations from a T. rex’s vocalizations if encountered in its natural environment.

**Image Credit.** *Noelle K. Moser*. ***Stan’s jaws gracefully agape showing his massive conical bone-crushing teeth.*** Houston Museum of Natural Science.

Stan provides an extraordinary insight into what could be considered one of evolution’s most advanced anti-tank weapons—a formidable predator characterized by its bone-crushing strength and armor-piercing teeth, which were capable of penetrating even the most well-defended dinosaurs. The ongoing debate about whether Tyrannosaurus rex was primarily a hunter or a scavenger continues to capture the interest of dinosaur enthusiasts. Dental adaptations clearly indicate that Stan was well-equipped to crush bones and consume prey whole with remarkable efficiency.

With conical, serrated, and recurved teeth resembling a set of razor-sharp steak knives, Tyrannosaurus rex was perfectly adapted to tear large chunks of flesh from its prey. Lacking molars and grinding teeth, it likely swallowed these meals whole while using its immense bite force to crush bone. The extraordinary fossil evidence from Stan has reshaped our understanding of T. rex, offering compelling insights that challenge the notion of this fearsome predator as merely an oversized scavenger.

I am a multi-disciplinary writer, paleontology blogger, and content creator. If you found this post engaging, be sure to check out my online writing portfolio to explore my extensive body of work.

References:

Kirk R. Johnson, Douglas J. Nichols, Joseph H. Hartman, 2002. “Hell Creek Formation: A 2001 synthesis”, The Hell Creek Formation and the Cretaceous-Tertiary boundary in the northern Great Plains: An Integrated continental record of the end of the Cretaceous, Joseph H. Hartman, Kirk R. Johnson, Douglas J. Nichols.

Larson, Peter and Carpenter, Kenneth. Tyrannosaurus Rex: The Tyrant King. Indiana University Press. Bloomington, Indiana. 2008.

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.

Chicxulub Impact: Catastrophic Collision That Ended the Age of Dinosaurs

Posted on August 27, 2024 by Noelle K. Moser

email: noellemoser@charter.net

**Image Credit.** *Noelle K. Moser.* ***Me standing at the base of Alamosaurus, a genus of Titanosaurian sauropod that lived during the late Cretaceous in Southwestern North America.*** *Perot National History Museum. Dallas, Texas*.

When we think about the time of the dinosaurs, two things stand out—Tyrannosaurus Rex and the extraterrestrial object that smashed into the planet – instantly ending the age of the dinosaurs. Earth has suffered several mass extinction events over the past 4 billion years. The Permian extinction is the deadliest, the end Cretaceous most famous.

An extraterrestrial object collided with Earth 66 million years ago. Only the impact with the proto-planet Theia, creating the moon more disastrous. What object collided with our planet, where did it come from, and what were the conditions after the impact? This article will answer these questions. It will also look closer at the event that ended the Age of the Dinosaurs. Catastrophe is never convenient. The last day of the dinosaurs began with a familiarity that had endured for 150 million years.

Image Credit: AI generated image created by WordPress and powered by OpenAI. **Tyrannosaurus Rex blinded by the incoming asteroid that would bring his reign to an end.**

What was the object that collided with earth?

The Chicxulub impact, 66 million years ago, is arguably the most famous asteroid collision in history. The impact released as much energy as 100 million nuclear bombs. It gouged a 120-mile wide, 12-mile-deep scar in the crust. It unleashed monstrous earthquakes, tsunamis, and firestorms. This colossal impact had profound effects on the planet. It led to the mass extinction of approximately 75% of species, including the dinosaurs.

The impact rang the Earth like a bell causing drastic climate changes. The collision triggered a nuclear winter, leading to a significant drop in global temperatures. This environmental catastrophe made it impossible for many species to survive, altering life forever.

Where Do Asteroids Originate?

Image Credit: ***Graphic of the solar system, the Oort cloud resides at the extreme edge of the Heliosphere.***

A lot of debris in our solar system is a result of its formation. Comets are dusty and icy remnants, whereas asteroids are mainly composed of rock. These collections of mostly harmless extraterrestrial bodies reside in several asteroid belts.

The main asteroid belt between Mars and Jupiter, The Kuiper Belt beyond the orbits of Uranus and Neptune, and the largest, the Oort Cloud, orbiting at 2,000 and 200,000 AU or 0.03 to 3.2 light-years away.

Image Credit: ***Three regions of asteroids exist within the solar system. These regions include the Main Asteroid Belt, Kuiper Belt, and the Oort Cloud.***

Disturbed by collisions and attracted by the sun’s gravity, some outer objects fall toward the inner solar system. These frozen bodies grace the night sky as bright comet nuclei with long, stunning, flowing tails. They pass by on calculated orbits held in place by the sun’s gravity.

While the orbit of most comet passes are cosmic spectacles, this has not always been the case. During the Late Heavy Bombardment (LHB) between 4.1 and 3.8 million years ago during the Neohadean and Eoarchean Eras, bodies from these asteroid regions collided with the moon.

The Formation of the Moon: Earth’s Early Cataclysm

The formation of the moon predates the Chicxulub impact by billions of years. According to the giant-impact hypothesis, the moon formed about 4.5 billion years ago when a Mars-sized body, referred to as Theia, collided with our molten planet. This titanic collision is so powerful that it ejected a significant amount of debris into orbit, eventually condensing by gravity to form the moon.

Similar orientation of the moon’s orbit and identical stable isotope ratios found in lunar and terrestrial rocks suggest a common origin. The moon’s relatively small iron core further supports this theory, indicating that the moon has lighter crust and mantle fragments from the impact

Where Did the Dinosaur Killing Asteroid Come From?

Image Credit: ***Artist rendition the Chicxulub Impact that killed the dinosaurs.***

Cosmic Fingerprint:

Not all asteroids contain the same material. There are three main composition classes of asteroids: C-types (carbonaceous), S-types (stony), and M-types (metallic). The asteroid believed to have killed off the dinosaurs 66 million years ago between the Cretaceous and Paleogene eras, known as the K/T boundary, can be determined by studying the Isotopic signatures.

Image Credit: The claystone layer containing 1000 times more iridium the upper and lower layers marking the boundary between the Cretaceous and Tertiary layers known as the K/T boundary. No dinosaurs are found above the Craterous layer. The keys to unlocking what the dinosaur killer lies in the rocks.

S-type asteroids are siliceous with a stony composition. These asteroids consist mainly of iron magnesium silicates. They are dominant in the inner part of the asteroid belt between the orbits of Mars and Jupiter between 2.2 – 3 AU (astronomical units about 93 million miles) but become rare farther out.

M-type asteroids are composed of metallic cores, predominantly Iron and Nickel, created by remnants of asteroids broken up by collisions over billions of years. M-asteroids orbit near the middle of the main asteroid belt between the orbits of Mars and Jupiter.

C-type asteroids are rich in carbon, clay, silicate rock, and ice, containing large quantities of carbon molecules. C-type asteroids orbit at the outer edge of the asteroid belt near Jupiter or beyond at 3.5 AU (330 million miles).

Image Credit: ***C-type asteroid known as 253 Mathilde, is the same class of asteroid that caused the extinction of the dinosaurs.***

Asteroids possess distinctive identifiers, akin to a cosmic fingerprint, that were found at the site of the mass extinction of the dinosaurs. In 1970, the perpetrator’s identity was discovered in the K/T layer, which marked the end of the Mesozoic era and subsequently the demise of the dinosaurs.

Within the K/T layer, high concentrations of iridium, a heavy metal, are found. Iridium is rare in the Earth’s crust but common in asteroids and meteorites. Analysis of the K/T boundary layer revealed the presence of shocked quartz, which dates back to 66 million years ago, in addition to heavy metal.

Image Credit: Shocked quartz, crystalized. Under intense pressure, the crystalline structure of the quartz crystal is deformed along planes inside the crystal. Shocked quartz is found worldwide, and occurs in the thin K/T boundary, which is distrbibuted worldwide.

While quartz is abundant in the Earth’s crust, shocked quartz is not. The only natural process capable of creating shocked quartz is an extraterrestrial impact. The chemical analysis of the impact debris indicated that the asteroid responsible was a C-type, clay-rich mudball containing materials from the dawn of the solar system, located just beyond Jupiter. The question remains. Where is the impact crater?

Image Credit: Crater in Arizona that was created 50,000 years ago by a nickle-iron asteroid 160 feet in diameter. At speeds of 29,000 mph, this house size object scarred the Earth. Although impressive, this crater is tiny compared to the crater left by the Chicxulub asteroid.

An asteroid capable of leaving a cosmic fingerprint on our planet would have been enormous beyond our comprehension. Despite its massive size, the crater left behind 66 million years ago was not easily found.

In the 1980s, Permex, a Mexican oil company, employed aerial topography software to explore the seafloor around the Gulf of Mexico. A decade later, scientists established that the large circular formation they had mapped was of a size matching that of the asteroid responsible for the extinction of the dinosaurs.

Image Credit: The seafloor topological map showcases formations below the water surface, notable the blue circular formation that caught scientists’ attention for its similarity in size to the theoretical Chicxulub cater caused by the asteroid that drove the dinosaurs to extinction.

Submerged beneath the water off the Yucatan Peninsula lay the Chicxulub crater, a lasting scar, and testament to the catastrophic impact of an asteroid, its name derived from the town located at its center. Analysis of cores from the sea floor confirms the cosmic fingerprint and origin of the K/T boundary layer, solidifying the crater’s status as a tangible reminder of the asteroid’s devastating trajectory.

Image Credit: ***Chicxulub Crater left by the C-type asteroid that caused the demise of the Mesozoic and subsequently the dinosaurs.***

One of Earth’s largest and best-preserved impact craters, the Chicxulub crater, measures 120 miles in diameter and 12 miles deep. The immense asteroid that created this crater is difficult to comprehend. The fossil record and K/T layer offer a glimpse into the final day of the dinosaurs, forever preserved in stone.

Impact and How the Dinosaurs Died:

Image Credit: ***Sculpture in the central park of Chicxulub Puerto, Yucatan, Mexico, on the suspected site of the impact of the meteorite that contributed to the extinction of dinosaurs 66 million years ago.***

Catastrophe is never convenient. Neither the dinosaurs nor the other organisms expected it. Life proceeded on that fateful day just as it had the day before and the day before that, stretching back through the millions of years. The last day of the dinosaurs began with a familiarity that had endured for 150 million years. (Black, 2022)

The Cretaceous period’s final day was set in motion years prior by a chance collision beyond Jupiter’s orbit, ultimately leading to the demise of Earth’s creatures, the iconic Tyrannosaurus Rex, Triceratops, and flying reptiles, who were in the wrong place at the wrong time.

**Image Credit:** *Noelle K. Moser.* Tyrannosaurus Rex Mor 555. Living during the last days of the Cretaceous era would have given T-rex a firsthand account of the C-type clay mudball that impacted the Yucatan Peninsula 66 million years ago, ending the reign of the dinosaurs. National Museum of Natural History. Washington, D.C.

Approximately 66 million years ago, a colossal C-type clay-rich mudball measuring six miles wide and weighing a trillion tons hurtled through our solar system at a staggering velocity of 45,000 miles per hour. This enormous object triggered a catastrophic chain of events that led to the most massive extinction in the history of our planet, ultimately causing the demise of the dinosaurs after slamming into the shallow seas near the Yucatan Peninsula at an incredible speed of 60 times the sound barrier.

As the asteroid screamed through the atmosphere, it unleashed an energy equivalent of 6 million times the magnitude of Mt. St. Helen’s 1980 eruption. Its trailing edge remained at an altitude of 35,000 feet, the same height as airliners in flight, at the instant of impact.

The plume of debris and initial impact would have created a hellish environment on Earth, with nothing surviving within a 1000-mile radius. The intense heat generated by the collision would have been equivalent to the sun’s intensity, resulting in the complete vaporization of all organic matter in the impact zone.

The asteroid’s impact on the shallow seas displaced around 500 billion tons of debris, with some fragments accelerating to 25,000 miles per hour and possibly attaining escape velocity, suggesting that some ejecta from the Yucatan Peninsula may have reached lunar orbit.

The immediate impact had far-reaching and devastating consequences. The temperature at the impact zone peaked at 16,000 degrees Fahrenheit, melting rock, and the expulsion of molten projectiles at supersonic speeds. A violent shockwave echoed through the land as superheated winds of 2,000 miles per hour radiated from the impact site, leaving a trail of destruction in their wake. Hell had come to Earth, and its creatures had no place to run.

It is challenging to constrain our imagination when contemplating something of this magnitude. The initial impact was overwhelming, but the aftermath was only beginning.

**Image Credit:** *AI generated image created by WordPress and powered by OpenAI.* ***Hell came to Earth and its creatures had no place to run.***

The impact of the massive asteroid in the ocean triggered a colossal tsunami, one of the largest ever witnessed on Earth. Generating a monumental splash from the shockwave, a 300-foot wall of water at hundreds of miles per hour crashed along the shores of Georgia, Mississippi, and Texas. On the other side of the world, dinosaurs died after the impact. The K/T layer holds the clue to the death of those dinosaurs.

Besides iridium and shocked quartz, the K/T layer comprises particles of soot distributed worldwide, amounting to several billion tons, comparable to the Earth’s total vegetation combusting instantaneously, meaning only one thing – a global inferno.

How does an entire planet catch fire? The impact’s intensity was so extreme that it hurled billions of tons of debris into the atmosphere, which orbited the globe before re-entering and causing a global atmospheric heating event that sparked forest fires on the opposite side of the world.

It was a disastrous day for the dinosaurs, as their enormous size made any location on the planet lethal. The dinosaurs were roasted alive, unable to hide in underground burrows like our ancestors. In cruel irony, the asteroid’s impact occurred at the worst possible location on the planet.

**Image Credit:** *AI generated image created by WordPress and powered by OpenAI.* The dinosaurs faced a disastrous day as their massive size made every location on Earth deadly. The dinosaurs had no protection and were burned alive. In cruel irony, the asteroid impact occurred at the worst possible location on the planet.

The few surviving dinosaurs confronted an even greater menace – abrupt climate change. The dust and debris from the impact enveloped the planet, plunging it into a prolonged nocturnal period lasting six months. The once vibrant blue planet, teeming with life, was transformed into a dismal gray shroud.

**Image Credit:** *AI generated Image created by WordPress and powered by OpenAI.* ***The once vibrant blue planet, teeming with life, was transformed into a dismal gray shroud.***

The presence of sulfur-bearing minerals in the Yucatan led to decreased global temperatures. Sulfur emissions poisoned the air, and subsequent sulfur dioxide reactions with atmospheric water formed sulfuric acid, resulting in increased solar energy reflections and planetary cooling.

As temperatures gradually returned to normal, plant life began to recover, but the lingering effects of sulfur dioxide caused acid rain, which damaged emerging leaves. Consequently, surviving dinosaurs faced starvation, leading to the total collapse of the food chain and the eventual demise of both herbivores and their carnivorous predators. For the dinosaurs, there was no coming back. After 150 million years of supremacy, the reign of the dinosaurs came to an end. The dinosaurs ruled the earth, but they could not defend themselves against the asteroid and its devasting effects.

The asteroid continued to have effects after the dinosaurs’ extinction. Global cooling eventually gave way to global warming due to the carbon dioxide from the rocks struck by the asteroid, equivalent to 3000 years of modern fossil fuel emissions. This carbon dioxide release was the final consequence of the impact, persisting for centuries and warming the planet, with temperatures rising by 20 degrees Fahrenheit, representing rapid global warming.

The asteroid’s impact did not entirely extinguish life. With the dinosaurs absent, early mammalian ancestors emerged from the burrows, paving the way for the rise of the mammals. One species would eventually transition from arboreal to bipedal locomotion and dominate the planet, much like the dinosaurs had for 150 million years. Although non-avian dinosaurs are extinct, their legacy endures through the birds, which carry the bloodline of the mighty T-rex.

**Image Credit:** *Noelle K. Moser.* ***Sketched by me. Our story begins because their story ends.***

The Chicxulub impact and the collision that created the moon are both pivotal events in Earth’s geological and biological history. They serve as stark reminders of the dynamic and sometimes violent nature of our solar system. These events have not only shaped the physical landscape of our planet but also the evolutionary path of life on Earth.

I am a multi-disciplinary writer, blogger, and web content creator. If you like this post, consider visiting some of my other site or Online Writing Portfolio.

The Kuntry Klucker – A blog about backyard chickens.

Introvert Cafe – A mental health blog

~ Noelle K. Moser ~

References:

BBC – Dinosaur asteroid’s trajectory was ‘perfect storm’

Black, Riley. The Last Days of the Dinosaurs: An Asteroid, Extinction, and the Beginning of Our World. St. Martin’s Publishing Company. New York, NY. 2022.

Harvard Gazette – New theory behind Chicxulub impactor that killed the dinosaurs

HHMI BioInteractive Video: The Day the Mesozoic Died: The Asteroid That Killed the Dinosaurs.

Kate Golembiewski,. “Dinosaur-Killing Asteroid Was Likely A giant Mudball, Study Says”. CNN. August 16, 2024.

Mario Fischer-Godde and Others. “Ruthenium Isotopes Show The Chicxulub Impactor Was A Carbonaceous-Type Asteroid. Science Vol. 385, No.6710. August 15, 2024.

My Visit to Natural History Museums across the nation.

**Image Credit:** *Noelle K. Moser.* ***Me peering through the fenestrae of Tyrannosaurus Rex MOR 555. Although non-avian dinosaurs are extinct, their legacy endures through the birds, which carry the bloodline of the mighty T-rex.*** *Cincinnati Natural History Museum. Cincinnati, Ohio.* 2024.

Carcharodontosaurus Saharicus: Shark-Like Teeth and Massive Size

Posted on August 19, 2024 by Noelle K. Moser

email: noellemoser@charter.net

Image Credit: ***Carchrodontosaurus Skull.***

Millions of years before Tyrannosaurus Rex roamed the earth, another group of gigantic meat-eaters ruled the land. This group of dinosaurs produced some of the largest carnivores, Giganotosaurus, Mapusaurus, Acrocanthrosaurus, and Tyrannotitan.

Roaming North Africa 99 to 94 million years ago, Carchrodontosaurus (CAR-car-oh-DONT-oh-SORE-us) reached massive sizes, some outweighing Tyrannosaurus Rex by a ton. While size alone places this theropod in the Dinosaur Hall of Fame, the most remarkable characteristic of this massive meat-eating machine is the teeth of this carnivore.

Image Credit: ***Chacharodontosaurus Life Restoration.***

Shark-Like Teeth of Charcharodontosaurus.

Image Credit: ***Carcharodontosaurus Blade-Like Tooth.***

Weighing seven metric tons, Carcharodontosaurus had a ferocious apatite, armed with 60 sharp recurved, serrated teeth that bear a striking resemblance to that of a great white shark – and inspiration for the name – this massive meat-eater effortlessly sliced and diced large titanosaurs which it hunted in family groups. Even more captivating was the discovery of Carcharodontosaurus.

Discovery of Carchrodontosaurus:

In 1699, Edward Lhuyd found a tooth thought to have belonged to a large extinct carnivorous fish. Subsequent studies showed that the tooth belonged to an unknown species of Megalosaurus. In 1824, William Buckland, an English Theologian, geologist, and paleontologist, discovered the first dinosaur fossil, Megalosaurus (meaning “great lizard”). The fossil recovered contained the lower mandible (jawbone) and teeth of a large theropod from the Middle Jurassic about 166 million years ago. William Buckland described the teeth as sharp, serrated, and jagged, similar to the shark tooth found by Edward Lhuyd nearly 100 years earli

Tracking across Egypt in 1914, German paleontologist Ernest Stromer and his expedition team excavated a partial skeleton of a large theropod with shark-like serrated jagged teeth described as Megalosaurus saharicus, belonging to a group of theropods called Megalosauridae.

Image Credit: ***Jawbone of Megalosaurus described and illustrated by William Buckland in 1824.***

After careful study, in 1931, Stromer announced that the tooth belonged to a new species of carnivorous theropod dinosaur he called C. saharicus (Carcharodontosaurus Saharicus). Unfortunately, the skeleton was destroyed by Allied bombing raids during the Second World War. C. saharicus was lost to science until 1995 when a complete skull was excavated from the Kem Kem Beds in Morocco.

Size:

Stromer hypothesized that C. saharicus was around the same size as the tyrannosaurid Gorgosaurus, which was 26–30 ft long, 39–41 ft head to tail, and weighed approximately 5–7 metric tons. Carcharodontosaurus saharicus is one of the largest known theropod dinosaurs and terrestrial carnivores.

Feeding and Diet:

Bite forces of Carcharodontosaurus and other giant theropods Acrocanthosaurus and Tyrannosaurus were analyzed showing that carcharodontosaurids had much lower bite forces than Tyrannosaurus despite being similar in size. A 2022 study estimated that the anterior (front teeth) bite force of Carcharodontosaurus was 11,312 newtons while the posterior (back teeth) bite force was 25,449 newtons, suggesting that it did not eat bones.

The shark-like teeth of Carcharodontosaurus acted like a meat slicer, while the conical-shaped teeth of Tyrannosaurus Rex crushed bone. Acrocanthosaurus (another carcharodontosaurid) relied on pack cooperation with a slice-and-dice approach to hunting. The theropods trailing behind a large herd of sauropods would take turns biting and slashing at the target; the objective was to keep the prey moving and bleeding. The lumbering prey, weakened through blood loss, exhaustion, and infections, would collapse under its weight. Like Acrocanthosaurus, this suggests that Carcharodontosaurus used this same hunting method.

Paleoenvironment:

Image Credit: ***The Tethys Ocean during the Mesozoic when the super content of Pangea began to break apart.***

Carcharodontosaurus fossils reside in Cretaceous-age formations across North Africa. During the Cretaceous, North Africa, bordered by the Tethys Ocean, occasionally flooded and created an environment of tidal flats and lush waterways. The seasonal monsoons created sub-tropical environments supporting diverse fauna. Unlike other regions, Cretaceous North Africa is an anomaly as several groups of meat-eating dinosaurs lived nearby. Fossil records show that niche diets allowed the habitat to support fewer herbivores per carnivore ratio. Fish-eating dinosaurs such as Spinosaurus hunted in the water while land-dwelling theropods hunted on land. Simply put, the carnivorous dinosaurs did to compete for food.

Image Credit: ***Life restoration of life during the Cretaceous. Carcharodontosaurus Saharicus at the center right.***

Extinction:

For unknown reasons, the tyrannosaurs (Abelisaurs in the Northern Hemisphere, Tyrannosaurs Rex in the Southern Hemisphere) replaced Carcharodontosaurus and the other predatory theropods Giganotosaurus, Mapusaurus, and Acrocanthosaurus. The remaining tyrannosaurs ruled the land for 3.6 million years until that fateful day 66 million years ago.

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

The Kuntry Klucker – A blog about raising backyard chickens

The Introvert Cafe – A Mental Health Blog

~ Noelle K. Moser ~

Resources:

Natural History Museum Carcharodontosaurus

Ransom-Johnson, Evan & Csotonyi, Julius. Dinosaur World. Kennebunkport, Maine, Applesauce Press, 2023.

Wikipedia: Charcharodontosaurus

My visits to Natural History Museums across the country.

Daspletosaurus: The Proto-Tyrant of Late Cretaceous

Posted on August 6, 2024 by Noelle K. Moser

email: noellemoser@charter.net

**Image Credit:** *Noelle K. Moser.* ***Silhouette of Daspletosaurus and skull of Tyrannosaurus Rex specimen MOR555 overlooking downtown Cincinnati.*** *Cincinnati Museum Center. Cincinnati, Ohio.*

During the Cretaceous Tyrannosaurs were the dominant force, the largest among them the mighty T-rex. Tyrannosaurus Rex was the largest, and heaviest terrestrial carnivore ever walking the earth. Millions of years before Tyrannosaurus Rex reigned as the king of the dinosaurs, another monster tyrant ruled the world. His name was Daspletosaurus (das-PLEE-toh-SORE-us). Dwarfed by Tyrannosaurus Rex, Daspletosaurus was the dominant predator of its time. What was this proto-t-rex, how did it become the tyrant of the late Cretaceous, and why did it become extinct? In the article, we will look at Daspletosaurus, the fierce lizard from the Cretaceous.

**Image Credit:** *Noelle K. Moser*. Daspletosaurus towering over Tyrannosaurus Rex (MOR555) skull. Notice the similarity and dental arrangement in the skulls. Boxy skulls with conical teeth are traits of tyrannosauroids. It is clear that these individuals are related on the same branch of the theropod family tree. *Cincinnati Museum Center. Cincinnati, Ohio.*

Daspletosaurs’s story begins in 1921 when paleontologist Charles M. Sternberg discovered the fossil of what was thought to be Gorgosaurus, another theropod on the tyrannosaur family tree. However, in 1970, it was determined this dinosaur was different and assigned to its genus. Daspletosaurus Torsus, “strong frightful reptile”, was assigned to this new tyrannosaur.

The disarticulated skeleton consisted of a complete skull, a forearm, two femurs, and a pelvis. It also included all of the neck, back, and tail vertebrae. Since its original discovery, only one other Daspletosaurus is known.

Daspletosaurus Torsus and its relative Daspletosaurus Horneri are similar in size. 30 feet from head to tail, 82 feet tall, and weighed about 3 tonnes. Compared to humans, Daspletosaurus is large but dwarfed by its predecessor, Tyrannosaurus Rex. T-rex was about 42 feet long, 12 feet tall at the hip, and tipped the scales at 8 tonnes.

Image Credit: Daspletosaurus size comparison.

A genus of tyrannosaurid dinosaurs Daspletosaurus is closely related to Tyrannosaurus rex, from which the clade name originates. This group includes small to massive coelurosaurian dinosaurs that evolved into Tyrannosaurus Rex.

Daspletosaurus Habitat:

Image Credit: ***Laramidia and Appalachia, two landmasses that eventually made-up North America.***

Home to daspletosaurus during the Late Cretaceous was a vast floodplain of the eastern coast of Laramidia. Laramidia and Appalachia are the two continents that would eventually become North America. During the Jurassic, these drifting continents were split by a vast ocean, the Interior Seaway. Along the Interior Seaway are five distinct and important formations encapsulating Daspletosaurus fossils. The Old Man Formation, Judith River Formation, Bear Paw Formation, and Dinosaur Park Formation. Situated in the Bad Lands of the western United States, these formations are present-day Montana and Lower Alberta, Canada.

Ceratopsians, hadrosaurs, Ornithosaurs, and other tyrannosaurs are entombed in the rocks near Daspletosaurus fossils. This suggests that these dinosaurs were contemporaries of Daspletosaurus and served as food for the dominant theropods at that time.

Why Did Daspletosaurus Go Extinct?

Daspletosaurus is known from 75 million years ago in the Campanian Late Cretaceous. The species suddenly disappeared 74 million years ago. After 5 million years of existence, it is unknown why Daspletosaurus went extinct. Competition with Tyrannosaurus Rex is one possibility climate change from volcanic activity is another. Whatever the reason, fossil evidence shows that Daspletosaurus disappeared, leaving Tyrannosaurus Rex to rule the land.

Daspletosurus was a fascinating theropod and an incredible link in the tyrannosaurus family as the tyrant before T-Rex.

**Image Credit:** *Noelle K. Moser.* ***Me standing next to Daspletosaurus Torsus and Tyrannosaurus Rex skull of specimen MOR555.*** *Cincinnati Museum Center. Cincinnati, Ohio*.

I am a multi-disciplinary writer, blogger, and web content creator. If you like this post, please visit some of my other sites or Online Writing Portfolio.

The Kuntry Klucker – A blog About Backyard Chickens

The Introvert Cafe – A Mental Health Blog.

Resources:

My Visit to Cincinnati Museum Center to study Daspletosaurus.

Holtz, Thomas R. Dr. Dinosaurs: The Most Complete, Up-To-Date Encyclopedia for Dinosaurs Lovers of all Ages. Random House. New York, NY. 2007. (pgs. 117, 124, 125, 126).

Pim, Keiron. Dinosaurs: The Grand Tour. Everything Worth Knowing About Dinosaurs from Aardonyx to Zuniceratops. The Experiment. New York, NY. 2019. (pgs. 302, 341).