Venturing back to the Late Cretaceous Period, we encounter Saurolophus, a dinosaur whose name, derived from Greek, means ‘Ridged Lizard’. This magnificent creature offers a captivating glimpse into a world over 66 million years ago.
Saurolophus, known for its distinctive crest and herbivorous habits, inhabited landscapes marked by profound geological and climatic shifts. Its existence during the Maastrichtian paints a vivid picture of the ancient ecosystems and underscores the evolutionary journey of these fascinating creatures.
Saurolophus Key Facts
| Keyword | Fact |
|---|---|
| Pronunciation | SOAR-oh-LOAF-us |
| Meaning of name | Ridged Lizard |
| Group | Ornithopoda |
| Type Species | Saurolophus osborni |
| Other Species | Saurolophus angustirostris |
| Diet | Herbivore |
| When it Lived | 72.1 to 66.0 MYA |
| Period | Late Cretaceous |
| Epoch | Maastrichtian |
| Length | 27.0 to 43.0 feet |
| Height | Approximately 13.0 feet |
| Weight | 12.0 tons |
| Mobility | Moved on four legs |
| First Discovery | 1911 by Barnum Brown |
| Described by | 1912 by Barnum Brown |
| Holotype | AMNH 5220 |
| Location of first find | Alberta, Canada |
| Also Found in | Mongolia, New Mexico, Wyoming |
Saurolophus Origins, Taxonomy, and Timeline
Saurolophus, a name that resonates with the echoes of ancient Greek, meaning ‘Ridged Lizard’, stands as a testament to the diversity and complexity of dinosaur life during the Late Cretaceous Period. This remarkable dinosaur, belonging to the Ornithopoda and nestled within the hadrosaurid, showcases a fascinating evolutionary journey.
The Tale of Two Species
Today, paleontologists recognize two valid species within the Saurolophus genus: the type species S. osborni and S. angustirostris. S. osborni, described by Brown in 1912, is known from a skull and skeleton, two other complete skulls, and fragments of additional skulls. This species, first discovered in North America, provides a crucial link in understanding the hadrosaurid family tree.
S. angustirostris, described by Rozhdestvensky in 1952, presents a slightly different story. Known from at least 15 specimens, this species was discovered in Mongolia and exhibits some distinct features when compared to its North American counterpart.
The existence of Saurolophus during the Maastrichtian (Late Cretaceous Period, approximately 72.1 to 66.0 million years ago) places it in a time of significant geological and climatic changes. This era, marking the twilight of the age of dinosaurs, saw the rise and fall of numerous species, with Saurolophus being one of the last to roam the earth before the mass extinction event.
Listen to Pronunciation
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Discovery of Saurolophus
In 1911, a significant discovery was made by Barnum Brown, a name synonymous with pioneering paleontological work. Brown unearthed the first described remains of Saurolophus, a nearly complete skeleton (AMNH 5220), now proudly displayed in the American Museum of Natural History. This skeleton, the first nearly complete dinosaur skeleton from Canada, was found in the Upper Cretaceous Horseshoe Canyon Formation, near Tolman Ferry on the Red Deer River in Alberta. The discovery was made in rocks dated to the early Maastrichtian, a crucial period in the Late Cretaceous.
Brown’s work was swift and meticulous. He not only described this new species but also assigned it its own subfamily, recognizing its unique place in the dinosaur lineage. Saurolophus quickly became an important reference point in the study of hadrosaurs, influencing the naming of related species like Prosaurolophus (“before Saurolophus“) and Parasaurolophus (“near Saurolophus“). However, despite its initial impact, further finds of Saurolophus in North America were limited.
Asian Discoveries: Expanding Our Understanding
The narrative of Saurolophus took a fascinating turn with discoveries in Asia. Initially, the findings were modest – a fragmentary ischium (part of the pelvic bone) from Heilongjiang, China. However, more substantial discoveries were on the horizon. Between 1946 and 1949, Russian-Mongolian paleontological expeditions unearthed a large skeleton in Mongolia’s Nemegt Formation, dating back to the early Maastrichtian Age. This skeleton was later described by Anatoly Rozhdestvensky as S. angustirostris, a new species of Saurolophus.
These Asian finds, particularly S. angustirostris, have become pivotal in our understanding of the Saurolophus genus. Numerous skeletons from various growth stages have been discovered, making S. angustirostris the most abundant Asian hadrosaurid. The differences between the North American S. osborni and the Asian S. angustirostris are intriguing. S. angustirostris had a longer skull and distinct scale patterns on its skin, suggesting possible differences in coloration and physical appearance between the two species.
Reevaluation and Species Distinction
The journey of understanding Saurolophus has been one of continuous discovery and reevaluation. For instance, S. kryschtofovici, initially thought to be a separate species, is now either considered dubious or synonymous with S. angustirostris. The distinction between S. osborni and S. angustirostris was further clarified in a 2011 reevaluation by Phil R. Bell. This study highlighted the need for a more comprehensive description of these species to fully appreciate their differences and similarities.The discovery and subsequent studies of Saurolophus have not only enriched our knowledge of this specific dinosaur but have also shed light on the broader hadrosaurid family and their evolution. Each new find adds a piece to the puzzle, helping us piece together the life and times of these fascinating creatures from a world long gone.
Mounted S. angustirostris skeleton at Nagoya City Science Museum
A photograph of the panel mount of the holotype of S. osborni, from Barnum Brown, 1913
Photo from the excavation of S. osborni in 1911
Skulls in Moscow Paleontological Museum
Cast of skull of Saurolophus angustirostris Size 1 m
Skull of the holotype specimen of S. osborni
Bones on the right side of the block show a certain degree of articulation, whereas bones on the left are disarticulated.
Left humerus of S. angustirostris MPC-D 100/764, showing multiple bite marks
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Saurolophus Size and Description
Saurolophus, a dinosaur known for its distinctive cranial crest and robust build, has left behind a wealth of skeletal remains that provide a clear picture of its size and physical characteristics. This section delves into the size differences between its two species and the unique features of its skull.
Size and Weight of Species
S. osborni: The Albertan Species
S. osborni, the species first discovered in Alberta, Canada, was a sizable creature. It measured approximately 27.0 to 28.0 feet in length, with its skull alone reaching about 3.3 feet. This species is estimated to have weighed around 3.0 tons, making it a formidable presence in its Late Cretaceous habitat.
S. angustirostris: The Larger Mongolian Counterpart
In contrast, S. angustirostris, discovered in Mongolia, was even larger. This species stretched to an impressive length of up to 43.0 feet, and there are reports of even larger remains. The weight of S. angustirostris is estimated to have potentially reached up to 11.0 tons. The largest known skull of this species measures 4.0 feet in length, indicating a significant size difference between the two species.
Short Description of Saurolophus
The most striking feature of Saurolophus is undoubtedly its cranial crest. Present even in young individuals, though smaller, this crest is long, spike-like, and projects upward and backward at about a 45° angle, starting from over the eyes. Often described as solid, the crest appears to be solid only at the tip, with internal chambers that might have played a role in respiratory and/or heat-regulation functions.
In adult specimens, the crests of both species have a rounded triangular shape in cross-section. The crest extends beyond the edge of the skull, with thin processes from the frontals and prefrontals running along its underside, likely providing structural support. The nasal bones almost completely make up the unique crest of Saurolophus, with a notable swelling at the end of the crest in S. angustirostris.
Saurolophus, with its significant size differences between species and its unique cranial features, stands as a fascinating subject in the study of dinosaur anatomy and evolution. These physical characteristics not only distinguish it from other dinosaurs but also provide insights into its lifestyle and behavior during the Late Cretaceous Period.
Saurolophus in detail
Saurolophus, a hadrosaurid dinosaur from the Late Cretaceous Period, inhabited environments rich in diverse plant life. This chapter delves into the specifics of its habitat, examining its diet, distinctive physical characteristics, and social behavior to better understand how it interacted with and adapted to its surroundings.
The Environment and Diet of Saurolophus
Saurolophus thrived in an environment that was as diverse as it was dynamic. As a herbivore, it had adapted to a life of grazing and browsing, feeding on a variety of plants available in its Late Cretaceous habitat. The structure of its skull allowed for a grinding motion akin to chewing, an adaptation that was crucial for processing plant material. Its teeth, packed into dental batteries containing hundreds of teeth, were continually replaced, ensuring efficiency in feeding. The broad beak of Saurolophus was ideal for cropping plants, while a cheek-like organ helped hold the food in place. Remarkably, its feeding range extended from ground level to about 13 feet above. This allowed it to access a wide array of vegetation.
The Crest: A Multi-Functional Feature
The distinctive spike-like crest of Saurolophus has been a subject of much speculation and study. While initially compared to the crest of a chameleon by Barnum Brown, who suggested it might have served as a muscle attachment point or a connection for a nonbody back frill, other interpretations have emerged over time. Some scientists, like Peter Dodson, have proposed that similar features in other duckbills might have been used for sexual identification. The hollow base of the crest in Saurolophus might have increased the surface area of the respiratory cavity, aiding in thermoregulation. James Hopson went further to suggest that the crest could have functioned as a visual signal, with the possibility of inflatable skin flaps over the nostrils acting as resonators and additional visual signals. This theory aligns with the idea that the crest played a role in social interactions and display behaviors.
Social Behavior and Ontogeny
Recent discoveries have shed light on the social behavior and developmental stages of Saurolophus. In 2015, a small nest containing several juveniles of S. angustirostris was described, providing insights into the early life stages of this species. These juveniles, found in the Dragon’s Tomb assemblage of the Nemegt Formation, were identified as perinates, indicating they were in the earliest developmental stage at the time of their deaths. The distinct crest found in adult Saurolophus was poorly developed in these young individuals, and other cranial features evolved as they grew.
Further evidence of social behavior in Saurolophus comes from the Dragon’s Tomb assemblage, where a large bonebed of S. angustirostris was discovered. This site, containing individuals of various sizes (juveniles, subadults, and adults), suggests that Saurolophus lived in social groups. The bonebed, reflecting a catastrophic mass-mortality event, provides the first evidence of gregariousness in this species. While direct evidence of social behavior in S. osborni is yet to be found, the gregarious nature observed in S. angustirostris and the widespread social behavior in hadrosaur suggest that Saurolophus may have exhibited similar social traits.
Contemporary Dinosaurs
One interesting dino which lived at the same time was the formidable Tarbosaurus. It was a carnivore predator whose size and strength were the stuff of legend. Saurolophus would have relied on its agility and herd mentality to navigate the dangers posed by this massive carnivore. Imagine a scene where a Tarbosaurus, towering and menacing, eyes a group of Saurolophus. The hadrosaurs, aware of their vulnerability, band together, their collective vigilance an unspoken pact against the looming threat.
In this Late Cretaceous tableau, Quaesitosaurus also played a significant role. This titanic Sauropod, larger than Saurolophus, was like a moving mountain in comparison. Despite their size difference, Saurolophus and Quaesitosaurus likely had a neutral relationship, coexisting without direct competition. Quaesitosaurus, with its towering neck, fed from the high canopies, a dining area far out of reach for the more earth-bound Saurolophus. This separation of feeding zones likely reduced any potential for conflict, allowing them to share the landscape harmoniously.
Therizinosaurus, another contemporary, presented an intriguing contrast. It had unique elongated claws and a body size roughly similar to Saurolophus. Based on this it might have appeared as a formidable competitor. However, Therizinosaurus was primarily a herbivore, and its unique claws were likely more suited for foraging than fighting. This suggests that any interactions between Saurolophus and Therizinosaurus were more about cohabitation than confrontation. Morover, each species would be adapting to utilize different resources within their shared environment.
Lastly, Bactrosaurus, smaller than Saurolophus, was a fellow herbivore. These two might have crossed paths often, perhaps grazing in the same areas. Bactrosaurus was not as physically imposing as Saurolophus. However, its presence in the ecosystem was a constant reminder of the diverse strategies life had evolved to survive.
Frequently Asked Questions
Saurolophus was a herbivore, feeding on a variety of plants available in its habitat during the Late Cretaceous Period.
The first Saurolophus fossil was discovered in Alberta, Canada, in 1911.
Saurolophus was likley primarily bipedal, though it could possibly use all four limbs for certain activities.
Saurolophus lived during the Late Cretaceous Period, specifically from 72.1 to 66.0 million years ago.
Saurolophus is distinguished by its elongated head with a unique crest, a feature not commonly seen in other dinosaurs.
Definitive evidence of its social behavior is lacking. However, it’s possible that Saurolophus lived in herds, as suggested by its habitat and behavior of similar species.
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 Saurolophus. However, please be aware that our understanding of dinosaurs and their world is constantly evolving as new discoveries are made.
Article last fact-checked: Joey Arboleda, 12-13-2023
Featured Image Credit: Illustration by L. Xing and Y. Liu., CC BY 2.5, via Wikimedia Commons
