Haplocanthosaurus: Enigmatic Sauropod of the Late Jurassic Era

Haplocanthosaurus: Enigmatic Sauropod of the Late Jurassic Era

Haplocanthosaurus stands out among dinosaurs, not just for its intriguing name but for the mysteries it holds. This dinosaur, whose name translates to “Simple Spined Lizard,” offers a fascinating glimpse into a world long gone. Discovered over a century ago, it continues to captivate the imagination of those who are passionate about the mesozoic era.

In this exploration, we’ll uncover the essence of Haplocanthosaurus, from its discovery to its habitat. It’s a journey back to the Late Jurassic Period, when this magnificent creature roamed the earth. As we piece together its story from fossil evidence and scientific research, we gain not only knowledge about it, but also a deeper understanding of the world it inhabited.

Haplocanthosaurus Key Facts

Meaning of nameSimple Spined Lizard
Type SpeciesHaplocanthosaurus priscus
Other SpeciesHaplocanthosaurus delfsi
When it Lived155.7 to 145.0 MYA
PeriodLate Jurassic
EpochLate/Upper Kimmeridgian to the top of the Early/Lower Tithonian
Length49.0 feet
Height46.0 feet
Weight14.1 tons
MobilityMoved on all four
First Discovery1903 by Edwin Delfs
Described by1903 by John Bell Hatcher
HolotypeCM 572
Location of first findMorrison Formation, Colorado
Also found inUtah, Wyoming

Haplocanthosaurus Origins, Taxonomy and Timeline

Haplocanthosaurus, whose name intriguingly means “Simple Spined Lizard,” has a unique place in the dinosaur taxonomy. Initially categorized as a cetiosaurid, it was later reclassified by José Bonaparte in 1999 into its own distinct family, the Haplocanthosauridae. This shift was due to its unique spinal structure, setting it apart from other  pods.

An artistic illustration of Haplocanthosaurus, a genus of sauropod dinosaur. The image depicts the dinosaur with its long neck and robust body, showcasing its quadrupedal stance. Haplocanthosaurus, known for its large size and herbivorous diet, lived during the Late Jurassic period. This illustration highlights its distinctive physical features and serene demeanor, providing a glimpse into its appearance and lifestyle.

The evolutionary relationships of Haplocanthosaurus are a subject of ongoing debate and study. Phylogenetic analyses have yielded varied results. Some position it as more primitive than the neosauropods, a group known for some of the largest land animals in history. Others suggest it might be an early macronarian, potentially related to the ancestors of larger sauropods like Camarasaurus and the brachiosaurids. There’s also a perspective that sees it as closely related to diplodocoids, akin to the well-known Diplodocus.

While the type species is named Haplocanthosaurus priscus, the genus have been further diversified with the recognition of another species in 1988, Haplocanthosaurus delfsi. This addition underscores the diversity within the Haplocanthosauridae and provides more layers to our understanding of these dinosaurs.

Living during the Late Jurassic Period, specifically from the Late Kimmeridgian to the Early Tithonian, Haplocanthosaurus existed approximately between 155.7 and 145.0 million years ago. This era was a time of significant change and diversification among dinosaurs, particularly sauropods. The unique characteristics and somewhat ambiguous phylogenetic position of Haplocanthosaurus add an interesting dimension to our understanding of sauropod evolution during this period.

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Discovery & Fossil Evidence

The discovery of Haplocanthosaurus dates back to 1903, a significant year that marked its entry into the scientific world. It was Edwin Delfs who first stumbled upon its remains in the Morrison Formation of Colorado, USA, a location renowned for its rich fossil deposits.

Later finds have extended our knowledge about this dinosaur, with additional fossils unearthed in regions like Utah and Wyoming. These discoveries have not only expanded the geographical range of Haplocanthosaurus but also provided more insights into its physical characteristics and lifestyle.

The fossils of this dinosaur, primarily consisting of vertebrae and some limb elements, have been relatively well-preserved. The holotype, CM 572, is particularly notable for its completeness and the insights it offers into the dinosaur’s anatomy. These fossil remains have been instrumental in piecing together the puzzle of Haplocanthosaurus’s existence.

Haplocanthosaurus Size and Description

Haplocanthosaurus, a unique member of the Sauropoda, stands out for several distinctive features. Its dorsal vertebrae, the bones forming the spine along the back, are notable for their lack of certain laminae – essentially, they’re missing some bony ridges found in other sauropods. This might sound technical, but it’s like having a backbone that’s simpler in structure compared to its relatives.

A detailed skeletal reconstruction illustration of Haplocanthosaurus, showcasing its full body structure. The image highlights the elongated neck, robust limbs, and lengthy tail characteristic of this Late Jurassic sauropod dinosaur. This reconstruction provides valuable insights into the anatomy, posture, and physical adaptations of Haplocanthosaurus, emphasizing its significant size and distinctive skeletal features.
IJReid, CC BY 4.0, via Wikimedia Commons

Another striking feature is the elongate intrapost-zygapophyseal laminae. In simpler terms, this refers to the long, supporting structures between the vertebrae, which play a role in the flexibility and movement of the spine. Additionally, the dorsal transverse processes – the bony projections where muscles and ligaments attach – are oriented in a way that they almost reach the height of the neural spines, the upward projections on each vertebra. This unique orientation could have implications for how this dinosaur supported its body and moved.

Lastly, the scapular blade, part of the shoulder bone, is expanded at the distal end (the end farthest from the center of the body), both dorsally (upward) and ventrally (downward). This might indicate a strong and robust shoulder structure, possibly to support a large forelimb or facilitate certain movements.

Size and Weight of Type Species

In terms of size, Haplocanthosaurus was relatively modest for a sauropod. While some of its contemporaries in the Morrison Formation reached lengths over 66.0 feet, this dinosaur was smaller, stretching to about 49.0 feet in length. As for its weight, it tipped the scales at an estimated 14.1 tons.

This size places Haplocanthosaurus on the smaller end of the sauropod spectrum, especially when compared to some of the colossal dinosaurs of its time. However, its size doesn’t make it any less significant. In fact, it offers a unique perspective on the diversity and adaptability of sauropods during the Late Jurassic Period.

Contemporary Dinosaurs

Haplocanthosaurus lived alongside some of the most iconic dinosaurs of the Jurassic Period, each playing a unique role in the ecosystem they shared.

Allosaurus on the other hand, a fearsome predator, was like the lion of the Jurassic savannah. Larger and more menacing than Haplocanthosaurus, it was a constant threat. Imagine the tension in the air as a Haplocanthosaurus herd cautiously drank from a river, ever watchful for the tell-tale signs of an Allosaurus ambush. These interactions were a daily reality, a delicate dance of predator and prey, where Haplocanthosaurus had to constantly be on guard.

But not all contemporaries were a threat. Apatosaurus, another gentle giant, was roughly the same size as our Haplocanthosaurus. They likely shared feeding grounds, their long necks reaching up to the tallest trees, stripping them of their foliage. It’s easy to picture these peaceful giants coexisting, perhaps even communicating in their own way, forming a bond over their shared love for lush, Jurassic greenery.

Then there was Stegosaurus, smaller than Haplocanthosaurus but no less significant. With its spiked tail and plated back, it roamed the same territories, though it likely fed on different plants, closer to the ground. This difference in diet meant they weren’t direct competitors for food, allowing for a harmonious coexistence. Diplodocus, another contemporary, shared more similarities with our main dinosaur, both being part of the sauropod family. Their interactions were probably more about sharing space than competing for it, painting a picture of a diverse yet interconnected Jurassic world.

Interesting Points about Haplocanthosaurus

Haplocanthosaurus in its Natural Habitat

Haplocanthosaurus thrived in a world vastly different from ours. During the Late Jurassic Period, it inhabited regions that are now part of North America. The landscape was dominated by lush vegetation, providing ample food sources for this herbivorous giant. The climate was likely warm and humid, supporting a diverse ecosystem.

As a plant-eater, Haplocanthosaurus fed on the abundant vegetation of its time. Its long neck would have been advantageous in reaching high foliage, while its size could have deterred potential predators. The social behavior of this dinosaur is not well-documented, but like many sauropods, it might have lived in herds for added protection and social interaction.

The presence of Haplocanthosaurus would have had a significant impact on its environment. Its feeding habits could have shaped the vegetation patterns, while its movement across the landscape would have influenced the soil and plant growth. This dinosaur was not just a passive inhabitant of its world but an active participant in shaping the ecosystem around it.

Frequently Asked Questions

What does its name mean?

The name means “Simple Spined Lizard,” reflecting its unique vertebral structure.

When did it live?

It lived during the Late Jurassic Period, approximately 155.7 to 145.0 million years ago.

What did it eat?

As a herbivore, it primarily fed on the lush vegetation of its time.

Where were its fossils found?

Its fossils have been discovered in the Morrison Formation of Colorado, and also in Utah and Wyoming.

How did it move?

It was quadrupedal, moving on all four feet, which suggests stability and endurance.

What is known about its social behavior?

While not much is known, it might have lived in herds like many other sauropods.


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 Haplocanthosaurus. However, please be aware that our understanding of dinosaurs and their world is constantly evolving as new discoveries are made.

This article was last fact-checked: Joey Arboleda, 11-29-2023

Featured Image Credit: FunkMonk (Michael B. H.), CC BY-SA 3.0, via Wikimedia Commons