Elrhazosaurus, a captivating dinosaur from the Early Cretaceous Period, once roamed the region now known as Niger, Africa. This herbivorous dinosaur, discovered in the Elrhaz Formation, provides a unique glimpse into the African Cretaceous ecosystem. 

The Elrhaz Lizard, as it is aptly named, draws interest not only for its well-preserved fossils but also for the ecological context in which it lived. Its existence during the Aptian, approximately 125 to 113 million years ago, places it among an intriguing array of contemporaneous dinosaurs. 

Elrhazosaurus Key Facts

Elrhazosaurus Origins, Taxonomy and Timeline

Elrhazosaurus, named after the Elrhaz Formation in Niger where its fossils were first discovered, literally means “Elrhaz Lizard.”

Taxonomically, Elrhazosaurus belongs to the group Ornithopoda, a clade of herbivorous dinosaurs known for their bipedal stance and varied sizes. Within this group, it is classified under the family Dryosauridae, which includes other small to medium-sized, fast-moving herbivores. Only one species, the type Elrhazosaurus nigeriensis is included within the genus.

Elrhazosaurus lived during the Aptian (Early Cretaceous from about 125.0 to 113.0 Ma). This time frame places it within a vibrant and dynamic ecosystem, rich with various flora and fauna. Understanding the timeline of its existence helps paint a broader picture of the environmental conditions and evolutionary pressures that shaped its development.

Discovery & Fossil Evidence

The first fossils of Elrhazosaurus were unearthed in 1973 by Philippe Taquet in the region of Gadoufaoua, located in the Republic of Niger, Africa. This initial discovery included the full left femur and a partial right femur. The quantity of the remains is scarce. The holotype, the left femur cataloged as MNHN GDF 332, remains one of the primary sources of information about this dinosaur.

Originally, the fossil were published under the name Valdosaurus nigeriensis in 1982 by Philippe Taquet and Peter Galton. Valdosaurus canaliculatus (the type species of Valdosaurus) is from the United Kingdom, and at the time the close relationship between V. nigeriensis and V. canaliculatus was linked to intercontinental fauna exchanges. 

While doing a review of several European ornithopods in 2009, including Valdosaurus, P. Galton that V. nigeriensis, despite represented by a poor fossil record, should be assigned to its own genus, and he erected Elrhazosaurus nigeriensis. Re-assessment of historical taxa is often performed in modern research in paleontology.

Elrhazosaurus Size and Description

Dryosaurs are relatively small compared to some of its dinosaur contemporaries. Those dinosaurs had a slender, bipedal body with long legs, which suggests it was adapted for fast and agile movement. Its head was proportionately small with a beak-like mouth, ideal for a herbivorous diet.

Dryosaur’s neck is moderately long, leading to a streamlined body that ends in a stiff, elongated tail. The vertebrae and limbs indicate a creature built for speed, likely relying on quick movements to evade predators. their skin, though not preserved in fossils, was probably covered with scales, typical of other ornithopods. They moved primarily on two legs, making them efficient and nimble foragers.

Size and Weight of Type Species

Based on the femur mesurement Elrhazosaurus nigeriensis was relatively small but well-adapted to its environment. Measuring about 6.6 feet in length, it was a modest-sized dinosaur. Its height at the hips was approximately 2.6 feet, giving it a low center of gravity that likely contributed to its stability and agility.

Weighing around 70.0 pounds, Elrhazosaurus was lightweight compared to many of its dinosaurian peers. This light build, combined with its bipedal stance, suggests it was a fast mover, capable of quick sprints to escape predators or to forage efficiently. Despite its smaller size, its physical adaptations made it a successful herbivore in its Early Cretaceous habitat.

Contemporary Dinosaurs

Present in this period were Suchomimus and Baryonix, large theropods, known for being primarily piscivore, feeding on fish from nearby rivers and lakes. This dietary difference allowed it to coexist with herbivorous dinosaurs like Elrhazosaurus likely without direct competition for food resources. Suchomimus was found in Niger (Tenere desert) but Baryonix was more widespread, with fossils of a couple of species found in Europe and South America. However, while fishes have been found in the body cavities of Baryonix, one specimen had also an Iguanodon preserved in its belly, showing complex feeding habits.

One of the contemporaries of Elrhazosaurus was Nigersaurus. This dinosaur, with its distinctive broad, flat snout, was also a herbivore. Unlike Elrhazosaurus, Nigersaurus had hundreds of small teeth adapted for grazing low-lying vegetation. Their coexistence suggests a rich and diverse plant ecosystem capable of supporting multiple herbivorous species.

Another dinosaur that shared the landscape with Elrhazosaurus was Ouranosaurus, an iguanodon from the Tenere desert in Niger. This dinosaur, larger and more robust than Elrhazosaurus, had a distinctive sail on its back. Both dinosaurs likely occupied different niches within the same environment, with Ouranosaurus perhaps feeding on higher vegetation, reducing direct competition with Elrhazosaurus.

Eocarcharia, found in the same geological formation than Elrhazosaurus, further diversified the dinosaur fauna of the region. This theropod predator would have been a threat to herbivorous dinosaurs, including Elrhazosaurus. The presence of such predators indicates a complex food web and dynamic interactions within the ecosystem.

Interesting Points about Elrhazosaurus

Elrhazosaurus in its Natural Habitat

Elrhazosaurus lived in a warm, semi-arid environment during the Early Cretaceous Period. The climate supported a variety of vegetation, including ferns, cycads, and early flowering plants. These plants provided ample food sources for herbivorous dinosaurs like Elrhazosaurus. The geography featured open plains interspersed with river valleys, creating a diverse habitat for various dinosaur species.

As a herbivore, Elrhazosaurus’s diet consisted mainly of low-lying plants. Its beak was well-adapted for cropping vegetation close to the ground, and its teeth were suited for grinding tough plant material. Moving on two legs, it was a nimble and efficient forager, capable of covering large areas in search of food. Its speed and agility were key survival traits in a landscape that included numerous predators.

Elrhazosaurus likely lived in small herds, a common behavior among herbivorous dinosaurs for protection against predators. Its social behavior, combined with its physical adaptations, provided it with a strategic advantage in evading threats. The dinosaur’s keen senses, such as sharp eyesight and hearing, would have been crucial for detecting danger and communicating with other herd members. Through its interactions with the environment and other species, Elrhazosaurus played a vital role in shaping the prehistoric ecosystem.

Frequently Asked Questions

Sources

The information in this article is based on various sources, drawing on scientific research, fossil evidence, and expert analysis. The aim is to provide a comprehensive and accurate overview of Elrhazosaurus.

Article last fact checked: Joey Arboleda, 06-30-2024

Featured Image Credit: Nobu Tamura, CC BY-SA 4.0, via Wikimedia Commons