Beneath the ancient skies of the Early Jurassic, a remarkable creature known as Pulanesaura roamed what is now southern Africa. Its name, meaning “Rain-maker Lizard,” reflects both the conditions of its discovery and its symbolic connection to nature’s cycles. This herbivorous dinosaur occupied a critical moment in evolutionary history, bridging the gap between earlier sauropod ancestors and the massive giants that would dominate later periods.

Fossil evidence paints a picture of a species figuring out how to best navigate its environment, finding that adaptive “sweet-spot” between increasing body-size (and appetite) and maneuverability. Showcasing several unique traits that set it apart from contemporaries, Pulanesaura offers paleontologists key insights into a crucial period in the early evolution of sauropod dinosaurs. This article delves into the origins, discovery, and life of this fascinating dinosaur, as well as the ecosystem it inhabited.

Pulanesaura Key Facts

Pulanesaura Origins, Taxonomy and Timeline

The name Pulanesaura, derived from the Sesotho word pulane (“rain-maker”), pays homage to the conditions surrounding its discovery. Fossil excavations occurred during a period of heavy rainfall, which imbued the process with symbolic significance. The latter part of its name, saura, is Latin for “lizard,” a common suffix for dinosaurs. Together, the name reflects both the natural environment of its unearthing and the animal’s place within paleontology.

This dinosaur belongs to the family Sauropodiformes, a group that represents transitional forms between smaller basal sauropodomorphs and the gigantic sauropods that would later dominate. Its type species, Pulanesaura eocollum, was described based on a fragmentary holotype individual, revealing a fascinating but frustratingly incomplete glimpse into its anatomy. Unlike its predecessors, Pulanesaura appeared to show adaptations for a fully (obligate) quadrupedal lifestyle, a key hallmark of true sauropods.

Pulanesaura lived during the Early Jurassic, specifically from the base of the Hettangian to the top of the Sinemurian Epochs, approximately 201.3 to 190.8 million years ago. This period marked a transformative phase in Earth’s history, as ecosystems began recovering from the Triassic-Jurassic extinction event. The evolutionary adaptations seen in Pulanesaura illustrate the diversification of herbivorous dinosaurs during this era.

Discovery & Fossil Evidence

The discovery of Pulanesaura occurred in 2014 on Farm Spion Kop 932, located in the Senekal District of South Africa’s Free State. Paleontologist Adam Yates led the excavation, uncovering a significant portion of the dinosaur’s skeleton despite challenging weather conditions. These remains were later described in 2015 by a team including myself, Adam Yates, Johann Neveling, and Jonah Choiniere.

The holotype specimen, cataloged as BP/1/6982, consists of an anterior dorsal vertebra, missing only the tip of the neural spine. Additional referred material includes two isolated teeth, a middle cervical vertebra, five back vertebral arches, a single right dorsal rib, three tail vertebrae, a left clavicle, a distal right humerus, a left ulna, possibly the fourth right middle hand bone, three ischia, a left and a right shinbone, and two hindlimb first claws. These remains were found in close association, within an area of three to three and a half meters, in fine, red mudstone. The consistent morphology across specimens and the lack of conflicting traits suggest they all belong to the same species. This comprehensive set of fossils provides invaluable insights into the anatomy and evolutionary significance of Pulanesaura.

Pulanesaura Size and Description

Short Description of Pulanesaura

This early sauropod displayed a body plan that hinted at optimizations for a fully quadrupedal lifestyle. Its elongated forelimbs supported a long neck and small head, characteristic of herbivorous dinosaurs. Its teeth had coarsely wrinkled enamel, typical of later sauropods. The vertebrae were specialized for weight-bearing and flexibility, hinting at its reliance on low-to-mid-growing vegetation for sustenance. Its tail likely served as a counterbalance, while the overall body shape suggested a slow-moving but steady creature, well-suited for its environment.

Exact measurements of Pulanesaura remain uncertain due to incomplete fossil evidence. Estimates suggest it was smaller than later sauropods, reflecting its transitional evolutionary status.

The Dinosaur in Detail

Pulanesaura’s unique adaptations mark it as a critical step in sauropod evolution. As the earliest herbivorous dinosaurs, sauropodomorphs likely relied on their primitively bipedal posture to help them reach as much vertical forage as their combo of long-hindlegs-and-neck allowed. Even the very largest non-sauropod-sauropodomorphs, weighing in at several tons, appeared to have continued to rely on this behaviour. Retaining the flexed (elbows-out) forelimb that likely cushioned their post-rearing descent back to the ground.

In contrast, the forelimbs of sauropod dinosaurs were oriented directly below the body as a kind of vertical support strut with limited lateral flexion – what we call the “parasagittal” condition. The advantage of the parasagittal arrangement is that weight is distributed much more efficiently and safely at larger body sizes, with the limbs of all large quadrupedal mammals oriented in this manner.  

However, the early adoption of this strategy likely came with a bit of a trade-off: rearing with a columnar forelimb is probably a heck of alot less safe than rearing with one that could still bend outwards at the elbow. This is where we reckon – based on our interpretation of its remains – that Pulanesaura showed the incipient stages the sauropodan “solution” to this problem. By increasing the flexibility of their necks, we suggested that the earliest sauropods may have evolved a strategy in which most mobility during feeding was restricted to the neck.

Benefits of the Flexible Neck

While likely (initially) limiting how high they could reach for vegetation, the ability to feed without having to constantly move their great baulk around likely also meant less energy expenditure during meal times. Once this safer, more energy efficient body-plan was “fine-tuned” towards the end of the Early Jurassic, the upper-limit of sauropod body sizes was thrown wide-open, with sauropods ranking amongst the “highest browsers” the world has ever known!         

This adaptive experimentation in feeding and locomotion strategies highlights the dynamic nature of sauropodomorph evolution at the outset of the Jurassic.

Contemporary Dinosaurs

In the semi-arid floodplains of the Early Jurassic, Pulanesaura shared its habitat with diverse assemblage of early theropod, sauropodomorph, and ornithischian dinosaurs.  

Aardonyx, another sauropodiform, exhibited a fascinating mix of bipedal and quadrupedal movement. Its transitional adaptations indicate a species capable of shifting between walking styles depending on need, which contrasts with the firmly quadrupedal posture of Pulanesaura. This difference in locomotion suggests that these two herbivores occupied distinct ecological roles, minimizing competition and allowing both to thrive.

Scuttling through the underbrush was the agile “fabrosaurid” Lesothosaurus, a small, fleet-footed herbivore that relied on speed and maneuverability to evade predators. Unlike the grounded and robust Pulanesaura, Lesothosaurus lived a life on the move. Always darting between patches of vegetation and exploiting niches inaccessible to larger, slower species. Their coexistence reflects a dynamic interplay of size and survival strategies within the same environment.

Adding to the diversity was Lycorhinus, a heterodontosaurid with a unique dental arrangement. This dinosaur likely consumed a wide range of food, including both vegetation and possibly insects. Utilizing its specialized teeth to process food that might have been challenging for other herbivores. Its dietary flexibility stood in contrast to Pulanesaura’s likely focus on low-lying plants. Highlighting a complementary relationship that contributed to the ecosystem’s richness.

Looming as a potential threat was Dracovenator, a fearsome theropod and one of the top predators of the region. This carnivore likely hunted smaller herbivores like Lesothosaurus. However, it may have also targeted juvenile or vulnerable members of larger species such as Pulanesaura. Its presence underscored the constant survival pressures herbivorous dinosaurs faced, shaping their behavior and adaptations in response to predation risk.

Interesting Points about Pulanesaura

Pulanesaura in its Natural Habitat

The landscape that Pulanesaura inhabited was predominantly arid floodplain criss-crossed by a series of braided rivers. Vegetation was concentrated most heavily around these river channels. While likely fluctuating during successive flood and drought periods, they were nonetheless abundant enough to support a large community of varied herbivores. This landscape featured abundant low-growing vegetation, including ferns and cycads, which likely formed the bulk of its diet. As a quadrupedal herbivore, it would have browsed on these plants, using its long neck to reach food sources spread across a wide area.

Pulanesaura’s locomotion was steady and deliberate, with its strong limbs adapted for weight-bearing. It possibly traveled in small groups, offering some protection against predators like Dracovenator. Social behavior may have included cooperative grazing, helping it exploit the rich plant life of its habitat.

In shaping its ecosystem, Pulanesaura’s feeding habits may have influenced vegetation patterns, contributing to the cycling of nutrients in the soil. This interaction underscores its role as both a consumer and contributor within its environment.

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 Pulanesaura. 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, 12-14-2024

Featured Image Credit: National Geographic