The Late Triassic Period, spanning millions of years ago, witnessed the rise of many fascinating creatures, among them the earliest dinosaurs. One such dino was Ahvaytum, thought to be amongst the first of the (eventually) massive sauropodomorph dinosaurs.

Discovered in the rugged terrains of Wyoming’s Popo Agie Formation, this dinosaur offers a unique insight into the evolution and global distribution of the first dinosaurs. Its name, derived from the Shoshone word “Anva·tum,” meaning “long ago,” beautifully encapsulates its ancient origins.

Standing just a foot tall and stretching about three feet in length, this omnivorous dinosaur may not have been as imposing as its later relatives, but its evolutionary significance remains undeniable. As we delve into the life and times of this Late Triassic creature, Ahvaytum provides a window into a world teeming with both challenges and opportunities for survival.

Ahvaytum Key Facts

Ahvaytum Origins, Taxonomy, and Timeline

Ahvaytum’s name, which resonates with its ancient roots, derives from the Shoshone language and meand ‘long ago’, a nod to the region’s cultural and natural history. Pronounced “ah-vay-tum,” this name was chosen to honor its discovery in Wyoming and its status as a relic of a bygone era. The species name, bahndooiveche, further emphasizes its unique place in the fossil record.

Taxonomically, Ahvaytum is currently classified as a basal sauropodomorph within the family Saturnaliidae. This classification places it among the earliest ancestors of the massive sauropods that would dominate later periods. As a type species, Ahvaytum bahndooiveche stands alone without any other recognized species, underscoring its distinctive evolutionary characteristics.

Existing during the Carnian Epoch of the Late Triassic, Ahvaytum lived between 237.0 and 227.0 million years ago. This timeline situates it within a critical phase of dinosaur evolution when the first true dinosaurs began to diversify and adapt to their environments.

Discovery & Fossil Evidence

Ahvaytum’s story began in 2013 when a team of paleontologists uncovered its remains in Wyoming’s Popo Agie Formation. This site, named “Garret’s Surprise” for the field assistant that discovered it, presented as a small scatter of fossil material eroding out from an erosional window within the overlying (and much younger) Wind River Formation, providing a rare glimpse into the Carnian strata of North America. Amongst this material was the holotype specimen, UWGM 1975. This consisted of a single astragalus bone, preserving just enough anatomical detail to identify the new taxon as an early sauropodomorph and distinguishing it from early members of its saurischian sister-lineage: Theropoda (as well as early ornithischians and dinosauriform taxa such as herrerasaurids). Another notable find, a partial left femur (UWGM 7549), displayed dinosaurian and saurischian traits, though its incomplete state leaves some questions unanswered.

The femur’s features offer fascinating details, such as an offset head creating a concave profile beneath it, typical of dinosaurs. Rounded tubers and ridges on the bone hint at similarities to early sauropodomorphs like Saturnalia and species such as Herrerasaurus. However, cracks and abrasion on the specimen obscure finer diagnostic details. Despite the limited fossil evidence, these discoveries provide valuable insights into Ahvaytum’s structure and lifestyle, though much about its biology remains speculative.

Ahvaytum Size and Description

Short Description of Ahvaytum

Ahvaytum was a small dinosaur with a compact, agile frame. Its body featured a long neck and a relatively small head, which likely housed sharp teeth suitable for an omnivorous diet. The limbs were slender yet sturdy, adapted for bipedal locomotion, and its tail provided balance while moving. Although there is no direct evidence of skin impressions, it likely had a scaly exterior like other early sauropodomorphs.

Size and Weight of Type Species

The type species, Ahvaytum bahndooiveche, measured approximately 3.0 feet in length and stood just a 1.0 foot tall. Although the weight is not determined, this dinosaur can be considered as one of the smaller dinosaurs of its time. These proportions suggest a creature built for agility rather than brute strength, likely enabling it to evade predators and forage effectively.

The Dinosaur in Detail

Ahvaytum’s small size and (presumed) omnivorous diet are fairly par-for-the-course when it comes to the earliest dinosaurs, with the specialized herbivory and carnivory of later sauropodomorphs and theropods, respectively, only really coming to the fore during the subsequent Norian stage. Unlike the massive herbivorous sauropods of later periods, this early relative was less fussy when it came to meal times, likely supplementing a diet that consisted of insects and smaller vertebrates with the first exploratory nibblings at the foliage that would have abounded in its environment. 

The fossil evidence also points to well-developed limbs that enabled efficient movement, possibly allowing it to navigate through dense vegetation or escape from predators. While its skeletal structure lacks the grandeur of later sauropods, it offers a glimpse into the evolutionary experimentation of the Late Triassic.

Ahvaytum also provides a fascinating glimpse into the dispersal patterns of the newly emergent dinosaur group. It has long been the consensus that dinosaurs first split from their archosaurian ancestors within the southern landmasses of Gondwana around ~230 million years ago, only populating the northern Laursian landmass several million years later during the Norian. However, Ahvaytum has been dated to approximately 230 million years ago, making it comparable in age to the oldest dinosaur faunas of Gondwana, which are also from the mid-late Carnian period (approximately 233-230 million years ago). This challenges the hypothesis of a delayed dinosaurian dispersal out of high-latitude Gondwana, suggesting that – wherever it is that dinosaurs first arose – they wasted little time in trekking around the Pangean supercontinent! 

Contemporary Dinosaurs

Due to the scarcity of Carnian-age dinosaurs thus far found in North America, most of what we know about similarly-aged dinos comes from the Gondwanan landmass of South America. One such contemporary was Eodromaeus, a small but agile basal theropod that may have hunted in similar areas. Slightly larger, its predatory nature meant that it likely favoured a more-heavy diet than the herbivory-leaning Ahvaytum, possibly making for a tense coexistence in their diverse Carnian landscape.  

Lepidus, the oldest-known North American dino prior to Ahvaytum, was a nimble and carnivorous dinosaur considered one of the earliest representatives of Theropoda. Although existing slightly after Ahvaytum, its ancestors, likely possessed the same hunting tactics and swift movements, were possibly brought into direct competition with Ahvaytum. The two forms may have shared scrounging grounds, both relying on their speed and agility to capture similar prey, creating an ongoing rivalry for survival in a world of limited resources.

In contrast to these carnivorous neighbors, Azendohsaurus roamed the Late Triassic as a primarily herbivorous non-dinosaurian archosaur. Its plant-based diet set it apart from Ahvaytum, which may have helped avoid direct competition. While both species traversed the same land, their ecological roles remained distinct, allowing Azendohsaurus to thrive without infringing on the hunting grounds of the carnivorous species around it.

Lastly, Caseosaurus, a basal theropod, added another layer to the complexity of the ecosystem. Although existing slightly later in time, as a predator it might have targeted smaller dinosaurs like Ahvaytum, further shaping the survival strategies of these early species. With its size and hunting techniques, Caseosaurus would have posed a potential threat to the smaller theropods, influencing the delicate balance of life during the Late Triassic. Together, these diverse creatures coexisted, each playing a role in the intricate web of life during a formative era in dinosaur evolution.

Interesting Points about Ahvaytum

Ahvaytum in its Natural Habitat

Ahvaytum inhabited a Late Triassic landscape characterized by warm, arid conditions interspersed with seasonal rains. The Popo Agie Formation’s sedimentary rocks suggest a habitat of floodplains and river systems, supporting diverse vegetation ranging from ferns to gymnosperms. This environment provided ample resources for omnivores like Ahvaytum.

Its diet likely included a mix of plants and small animals or insects, showcasing its adaptability. Moving on two legs, this agile dinosaur could navigate its environment efficiently, whether foraging for food or evading predators. Social behavior remains uncertain, but it may have lived in small groups or solitary.

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 Ahvaytum. 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, 01-15-2024