April 4, 2022 Scott Kraus

Herrerasaurus Ischigualastensis- The One and Only Herrerasaurus

Herrerasaurus, pronounced huh-Rare-uh-Sore-us, is classified to the family of Herrerasauridae, designated as the oldest known dinosaurs.  The genus species type, Ischigualastensis, was marked by Osvaldo Reig in 1963, and named after the person credited with finding the first fossilized traces of this species.  Herrera was the name of the Argentinian credited with discovery of these first fossils in 1959 South America, so this dinosaur is commonly known among paleontologists and across the globe as “Herrera’s Lizard”.

Herrerasaurus is a member of the Theropoda suborder and clade, whose descendants include modern birds.  Some Theropod traits shared by Herrerasaurus are clawed feet, indications of feathers and egg brooding.    Herrerasaurus is known for being one of the first dinosaurs to roam land, and is considered a prime example of evolutionary adaptation.

It’s significant that although Herrerasaurus was formidable in its time, it was one of the earliest dinosaurs and subsequently, one of the smallest.  Fossils found of Herrerasaurus present with tooth marks and other indications of battle with larger opponents.

It is reported that remains of Herrerasaurus present as the most plentiful when compared to found remains of other Theropoda in the area.  This suggests and enforces that- while Herrerasaurus looked and ate like its larger descendants, Herrerasaurus itself was easy prey for larger existing land mammals and various large prehistoric birds as well- possibly Samrukia, Phorusrhacidae, or another terror bird known to roam, forage and prey on land and in the air, and often standing at 1–3 meters (3–10 feet) tall.

Quick Facts

What Did Herrerasaurus Look Like?

A monster of dinosaurs in its day- sharing Earth with some other clade mates such as Staruikosaurus, Chindesaurus, Eoraptor, Daemonosaurus, Tawa, and Neotheropoda- Herrerasaurus was built with light gait and heavy body.  Ranging in weight from 250 to over 500 pounds, this was a formidable species to its foes.  Equipped with razor-sharp teeth and claws on hand-like front feet or talons, Herrerasaurus was a significant threat to even those predators its own size.

Herrerasaurus combined elements of earliest birds and lizards.  Skin texture and covering was of a mixed texture with some areas of nodes- skin believed to be reminiscent of avian genetics, with indication of propensity for feathering.

The flat back of Herrerasaurus encouraged a speedy gait, and at 7—15 feet long and 4—7 feet tall, this small birdlike and reptilian dinosaur could move and jump quickly and attack with force, using its strong hindquarters as both a propellant source and a defense when necessary.

Herrerasaurus would be a menacing presence today, much heavier than most humans and carrying more power in its muscles and carriage than any big dog or horse.   Its feet were big and limber.  Today’s dog, chicken or human would have a hard time in not succumbing to the will of Herrerasaurus, despite its small size in comparison with future Theropoda.

What Did Herrerasaurus Eat?

The diet of Herrerasaurus likely consisted primarily of land rodents and mammals smaller or weaker than itself, making Herrerasaurus a known carnivore.  After recovery of fossilized sharp and serrated teeth, it became clear that meat was the naturally intended priority diet of Herrerasaurus.  However, a creature of various fame, Herrerasaurus likely also dined on various prehistoric insects as well as some plant material.

Over time, the Theropod class changed from a fairly strict carnivorous diet, to a more varied diet of wider range.  Species by species, dinosaurs evolved across a myriad of circumstances, changing diet as convenient and ultimately changing course in evolution.  Herrerasaurus was advanced in that its mandible incorporated a special hinge type joint about halfway along its length.  This joint enabled this carnivore to better hold on to struggling victims, and to have more control over action in hunting.   Many Theropods that existed in succession also had this hinge, or specialized adapted joint.

The eating style of Herrerasaurus can be compared to any bird or mammal.  In its valley and forest environment near the rivers of what is now South America, Herrerasaurus blended in well and lurked for its prey, jumping quickly with its powerful hind legs and when they prey escaped the initial jump, Herrerasaurus hips could carry it fast enough to chase down most prey of its size.   Distance did not inhibit Herrerasaurus, capable of distance treks in search of food which could be found in the more arid environments further from any source of water.  Herrerasaurus was agile and quick, and would utilize strong and crafty clawed forearms for grabbing, grasping, holding and ripping prey. Herrerasaurus boasts 4—toed “feet” that operate more as hands.

How Did Herrerasaurus Move?

Utilizing its springy digitigrade stance (standing and moving on the toes), Herrerasaurus had great power in its stride and gait.  One can image Herrerasaurus prowling, even sauntering about its territory practically care-free as it waits on some signal of prey before quickly jumping to action, and running when necessary to catch its prey.  Picking through vegetation with its arm-like front limbs as it snouts and powers through with its strong body, Herrerasaurus was capable of using its powerful strength to lash out, hold and pick at its prey when necessary.

Herrerasaurus’ forelimbs were half the length of the hind limbs, enabling much power to their hindquarters and much dexterity to the front.  The hips and legs of Herrerasaurus lent much to its mysterious heritage as a possible non-dinosaur.   Lizard-like (Saurischian) hip qualities afforded easy land movement to this adept and evolving species.   Herrerasaurus likely moved quickly at times when it wasn’t at rest.  Much like modern birds or lizards, early cold-blooded Theropoda conserved energy during down times of not hunting.

Where Did Herrerasaurus Live?

Before the land split by way of plate tectonics and continental drift, South America was simply part of the larger expanse of land known today as Pangaea (Greek, for “all lands” or “all earth).   Herrerasaurus, as one of the first in a long line of prehistoric dinosaurs, lived on this land of Pangaea and likely enjoyed a large expanse of territory.  The landscape during prehistoric times would have been quite different from what it is today.

Herrerasaurus is recovered from the Ischigualasto Formation in the Valley of the Moon National Park in San Juan, Argentina.  Today, the area is barren with hills of desert colors and similar to the landscape of the Petrified Forest National Park in Arizona, where additional Herrerasaurus remains have been found.

Pangaea, 230—200 million years ago, would have been a diverse territory and Herrerasaurus is believed to have existed primarily in the warmer volcanic areas of land, down in the valley and flood plains that were rich with vegetation and prey.

The Discovery of Herrerasaurus

South America is recognized as the original root area of prehistoric dinosaurs.  Herrerasaurus was first discovered on a South American ranch, in what is known as Argentina today.  The original specimen was discovered in 1959 by Osvaldo A. Reig and Victorino Herrera, and later named by Reig in 1963 to reflect the goat rancher Herrera.

Herrerasaurus waited many years to be decoded in more detail, as originally only bits of fossilized bones were found from various specimens, and no skull was found until 1988 when a team of paleontologists found a mostly complete skeleton with its intact skull.  From that time, scientists have been able to paint a clarified picture of life as it was for Herrerasaurus.  Still today scientists search for clues into the existence of Herrerasaurus.

Herrerasaurus the Enigmatic

Herrerasaurus possesses traits found in various dinosaur groups, along with traits which do not belong to any dinosaur group, but to those groups known as non-dinosaur, such as Archosaurs and Saurischians.  Recent scientific discovery has led to the knowledge that Herrerasaurus lineage combines elements of the earliest birds and lizards.  The evolutionary dexterity exhibited by Herrerasaurus has sparked major strides in modern understanding of biology, adaptability and evolution among species.  Herrerasaurus has found a place among the living as a model  example of adaptation through adversity.

The Significance of Herrerasaurus

Herrerasaurus has been a perplexing mystery to many, yet as scientists have uncovered periodic information through research, field discovery and testing, much has now been learned about the enigmatic existence of Herrerasaurus.

Primarily, Herrerasaurus can be regarded as one the most significant examples of convergent evolution known today. Herrerasaurus possesses signs of many related ornithischian and saurischian dinosaurs, and also possesses its own branch (clade) of ancestry.  Herrerasaurus were dinosaurs that experienced a rapid evolutionary radiation process of incorporating ecological and species specific diversity into its genetics over a short period of time – adaptive radiations like this commonly follow mass extinctions, after which species niches can be vacant and open space to fill.