Imagine walking through the verdant forests of the Early Jurassic, where towering ferns and conifers dominate the landscape. Amid this prehistoric greenery, Anchisaurus, a modest-sized basal sauropodomorph, quietly roamed. First discovered in 1855 in Springfield, Massachusetts, this dinosaur has fascinated paleontologists for over two centuries. Its name, meaning “Near Saurian (Lizard),” reflects the age in which it was discovered, with paleontologists still piecing together what precisely defines a “primitive” versus an “advanced” dinosaur.

Anchisaurus, with its unique blend of primitive and advanced features, provides a crucial link in our understanding of the early evolution and diversification of sauropodomorph dinosaurs. This herbivorous dinosaur, described by Edward Hitchcock Jr. in 1865, showcases the early adaptations that allowed Sauropodomorpha to become the largest land animals in history. As we delve into its origins, discovery, and distinct characteristics, we’ll uncover the story of this remarkable dinosaur and its place in the ancient world.

Anchisaurus Key Facts

Anchisaurus Origins, Taxonomy and Timeline

Anchisaurus, whose name translates to “Near Lizard,” reflects its transitional status in the evolutionary timeline. The name derives from the Greek words “agkhi,” meaning near or close, and “sauros,” meaning lizard. This naming likely highlights its original interpretation as basal taxon just outside of “true” dinosaurs.  

In terms of taxonomy, Anchisaurus belongs to the group Sauropodomorpha, occupying a position just outside of Sauropoda – the lock-necked behemoths that would go on to dominate the later Mesozoic. Although several other species have been added to the Anchisaurus genus over the years, ultimately none have passed final muster and Anchisaurus now just contains the type species Anchisaurus polyzelus. 

Anchisaurus lived during the Early Jurassic period, specifically from the Hettangian to the Sinemurian epochs, approximately 201.3 to 190.8 million years ago. This time frame marks a critical phase in dinosaur evolution, where early sauropodomorphs like Anchisaurus began to exhibit traits that would define the massive sauropods of the later Jurassic.

Listen to Pronunciation

To listen to the correct pronunciation of this dino’s name, check out this video.

Discovery & Fossil Evidence

The first discovery of Anchisaurus occurred in 1855, when workers were blasting a well for the waterhouse at the Springfield Armory. Unfortunately, these remains (cataloged as AM 41/109) were badly damaged due to the nature of their discovery, and it was only some years later during the 1880s, when additional specimens were discovered in a quarry in Manchester, Connecticut, that a better sense of the anatomy of Anchisaurus came to light. These specimens (YPM 208, YPM 1883/40313) were described by the famous Yale palaeontologist O.C. March in 1893, and together comprise most of the skeletal elements of Anchisaurus, including a skull, limb bones, and vertebrae.

These well-preserved bones have enabled detailed studies, shedding light on its physical characteristics and evolutionary significance. The fossils are critical in understanding the diversification and palaeogeography of sauropodomorph dinosaurs within the Early Jurassic – especially given the paucity of their fossils for this time period within the eastern United States.  

Anchisaurus Size and Description

Anchisaurus was a relatively small dinosaur compared to its later sauropod relatives. This dinosaur measured between 6.6 to 13.1 feet in length and stood about 1.5 feet tall at the hips. Its weight ranged from 60.0 to 70.0 pounds, reflecting its lightweight and agile nature. Anchisaurus was likely mostly bipedal, primarily moving on two legs, which gave it the ability to navigate its environment efficiently.

Short description of Anchisaurus

The body of Anchisaurus was slender and elongated, with a long neck and tail. Its head was small, equipped with leaf-shaped teeth suitable for a herbivorous diet. The neck vertebrae were elongated, allowing for a considerable range of motion, essential for feeding on across a range of vegetation. The limbs were robust, with the hind legs being significantly longer and stronger than the forelimbs, supporting its predominantly bipedal locomotory habit. The tail was long and flexible, likely used for balance.

Size and Weight of Type Species

The type species, Anchisaurus polyzelus, exhibited a range of sizes depending on age and growth stage. Adults typically measured between 6.6 to 13.1 feet in length and stood around 1.5 feet tall at the hips. Their weight varied between 60.0 and 70.0 pounds. These dimensions suggest that Anchisaurus was a small but agile herbivore, capable of moving swiftly through its forested habitat.

Various studies have provided slightly different size estimates, but they generally fall within this range. The variation in size among specimens indicates possible sexual dimorphism or differences in individual growth rates. These size estimates, derived from well-preserved fossils, offer a reliable picture of Anchisaurus’ physical characteristics and its role in the Early Jurassic ecosystem.

The Dinosaur in Detail

Anchisaurus possesses several distinctive features that highlight its adaptability and evolutionary significance. Its elongated neck presaged the preposterous lengths that this appendage would grow to in later sauropods – easily the most recognisable and binding trait of the group as a whole. The vertebrae in its neck were specially adapted to support this extension, providing both strength and flexibility, while letting the animal feed across a range of horizontal and vertical forage without constantly having to move about.

The limbs of Anchisaurus were particularly robust for its size. The strong hind legs suggest that it was capable of quick, agile movements, which would have been advantageous in evading predators and navigating its environment. The forelimbs, while shorter, were also strong and likely used for grasping vegetation or stabilizing its body while feeding.

These features have been crucial in studying the evolutionary transition from early sauropodomorphs to the giant sauropods that followed.

Contemporary Dinosaurs

Sharing the early Jurassic landscape with Anchisaurus was Podokesaurus, a small, bipedal carnivore that belonged to the Coelophysoidea. This predator likely hunted small animals and insects, adding a dynamic predator-prey relationship to the ecosystem. The presence of Podokesaurus suggests that Anchisaurus had to be vigilant and agile to avoid becoming prey.

Pegomastax, a small herbivorous ornithischian with distinctive teeth for processing plant material, also lived during the same period. Its diet likely consisted of tougher vegetation, complementing the feeding habits of Anchisaurus. This dietary specialization allowed both species to coexist without significant competition for food resources.

Another dinosaur that roamed alongside Anchisaurus was Dilophosaurus. This theropod, larger than Podokesaurus, was one of the first genuinely large carnivorous dinosaurs and a formidable predator in the Early Jurassic ecosystem. The presence of Dracovenator indicates a complex food web, where herbivores like Anchisaurus had to navigate a landscape filled with potential threats.

Interesting Points about Anchisaurus

Anchisaurus in its Natural Habitat

Anchisaurus thrived in a lush, forested environment during the Early Jurassic Period. The climate was warm, supporting a diverse array of plant life, including ferns, cycads, and conifers. These plants provided ample food sources for herbivorous dinosaurs like Anchisaurus, which used its long neck to reach high vegetation.

As a herbivore, Anchisaurus had a diet that consisted primarily of various types of vegetation. Its leaf-shaped teeth were well-suited for stripping leaves and processing plant material. Moving primarily on two legs, Anchisaurus was agile and capable of navigating through its forested habitat efficiently. Its bipedal locomotion allowed it to cover significant distances in search of food.

Socially, Anchisaurus may have lived in small groups or herds, providing protection against predators and increasing foraging efficiency. This behavior would have allowed them to navigate their environment with relative safety, signaling potential threats and – possibly – the location of new resources. Its keen senses, particularly sight and smell, were essential for detecting food and avoiding predators like Podokesaurus and Dracovenator.

The presence of predators in its environment meant that Anchisaurus had to be vigilant. Its agility and speed were crucial survival traits, enabling it to escape from threats. As a relatively small dinosaur, blending into the forested landscape provided a form of camouflage against larger predators. Anchisaurus likely played a significant role in its ecosystem, contributing to the control of vegetation and serving as prey for the carnivores of its time.

The dense forests and rich vegetation of the Early Jurassic provided a dynamic and complex habitat for Anchisaurus. The interplay between different dinosaur species, along with the diverse plant life, created a vibrant ecosystem. Anchisaurus, with its unique adaptations, thrived in this environment, shaping and being shaped by the intricate web of life around it.

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 Anchisaurus. 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, 07-02-2024

Featured Image Credit: Joseph Smit (1836–1929), Public domain, via Wikimedia Commons