Massospondylus

Discovering the Dinosaur: Massospondylus

Massospondylus (mas-oh-SPON-di-ləs) was a genus of sauropodomorph dinosaur from the Early Jurassic, around 200–183 million years ago. It was described by Sir Richard Owen in 1854 from remains found in South Africa and is one of the first dinosaurs to have been named.

Imagine stepping back in time to a world where dinosaurs roamed freely, and you come across Massospondylus. This fascinating creature has left behind a rich legacy, with its fossils scattered across continents like a puzzle waiting to be pieced together. From South Africa to Lesotho, Zimbabwe, Arizona’s Kayenta Formation, India, and Argentina, the story of this dinosaur is as diverse as it is intriguing.

But what exactly did Massospondylus look like? Was it a plant-eater or could it have been omnivorous? These questions have puzzled scientists for years. A 2007 study revealed that Massospondylus was actually bipedal, not quadrupedal as originally thought. This discovery opened up new avenues of research and challenged our understanding of early dinosaur locomotion.

With a slender body, long neck, and proportionally small head, Massospondylus was around 4-6 meters in length and weighed approximately 1000 kilograms. Its vertebral column consisted of nine cervical, 13 dorsal, three sacral, and at least 40 caudal vertebrae. The forelimbs were powerful, with broad upper ends of the humerus providing attachment areas for large arm musculature. The hand was short and wide, with a large thumb claw used for feeding or defense.

The skull of Massospondylus had numerous openings (fenestrae), reducing its weight and providing space for muscle attachment and sensory organs. The antorbital fenestrae were smaller than those seen in Plateosaurus, while the lateral temporal fenestrae were shaped like an inverted ‘T’. Tooth count varied between individuals, with four teeth per side on the premaxilla and 14-22 teeth on the maxilla.

Massospondylus may have had cheeks due to large holes for blood vessels on the surfaces of the jaw bones, similar to other early sauropodomorphs. However, some studies suggest that a horny beak was not present. The biology and behavior of Massospondylus remain unknown due to limited fossil evidence.

Classification and Evolution

The genus consists of seven named species, with only M. kaalae considered valid. The type species is M. carinatus. Other named species include: M. browni, M. harriesi, M. hislopi, M. huenei, M. rawesi, and M. schwarzi.

Many of these species have been reassessed over the years. For instance, M. browni, M. harriesi, and M. schwarzi were found in the Upper Elliot Formation of Cape Province, South Africa. They are based on fragmentary material and are regarded as indeterminate. M. hislopi and M. rawesi were named from fossils in India and South Africa, respectively.

Massospondylus remains have been found in various rock formations worldwide, including South Africa, Lesotho, Zimbabwe, Arizona’s Kayenta Formation, India, and Argentina. The genus is still the subject of scientific debate, with some scientists disagreeing on its position in the dinosaur evolutionary tree. Uniquely among dinosaurs, it had tiny palatal teeth.

Behavior and Environment

A 2007 study suggested Massospondylus used its short arms for defense, intraspecies combat, or feeding, possibly using its large pollex claw. Intraspecies studies indicated Massospondylus’ growth patterns were affected by environmental factors, with some individuals growing rapidly at a rate of 34.6 kg per year.

A diet likely consisted of herbivorous or omnivorous lifestyle, supplemented with small prey or carrion. Studies ruled out quadrupedal locomotion, suggesting a bipedal nature due to the limited range of motion in its forelimbs. Massospondylus possessed well-developed clavicles and joined them in a furcula-like arrangement.

Michael Cooper noted that zygapophyses in neck vertebrae were inclined, prohibiting horizontal movement of the neck, but this was contradicted by a recent study showing only basalmost cervicals had inclined zygapophyses allowing sufficient horizontal movement. In 1976, James Kitching found a clutch of 190-million-year-old Massospondylus eggs in South Africa, which were later extracted and analyzed.

The embryos showed characteristics that suggested they were near-hatchlings, with big heads, short necks, and tiny limbs. The discovery of hatching footprints confirmed their quadrupedality. Newly hatched juveniles from a second sauropodomorph, Mussaurus, also resembled embryonic Massospondylus, suggesting that quadrupedality was present in hatchlings.

Respiratory System and Environment

The Early Jurassic faunas and floras were similar worldwide, with conifers adapted for hot weather becoming common plants. Basal sauropodomorphs like Massospondylus likely had abdominal and cervical air sacs, according to a 2007 study.

Respiratory system studies found that many saurischian dinosaurs possessed hollowed-out cavities (pneumatic foramina) in their vertebrae and ribs, which may have served as a basic ‘flow-through ventilation’ system similar to modern birds. In a respiratory system for sauropods and theropods, neck vertebrae and ribs are hollowed out by the cervical air sac, upper back vertebrae by the lung, and lower back and sacral vertebrae by the abdominal air sac.

Massospondylus co-existed with temnospondyli, turtles, sphenodonts, rauisuchids, early crocodylomorphs, and mammals. It was found to have a diverse contemporary sauropodomorph fauna with six additional species. The theropod carnivore Dracovenator lived during the same period as Massospondylus and had been found in the Elliot Formation of South Africa.

As we continue to uncover more about Massospondylus, it becomes clear that this dinosaur was not just a relic from the past but a key player in understanding the evolution of dinosaurs. Its story is one of adaptation, survival, and the enduring mystery of prehistoric life.