Brazilian paleontologists have unveiled a groundbreaking discovery: a new genus and species of dragonosaurs, named Isodapedon varsalis. This newly identified member of the Hyperodapedontinidae family was based on a partial skull and lower jaw found in Triassic rock formations, highlighting the diversity of a group previously believed to be less varied.

During the Late Triassic, rhynchosaurs were among the most prevalent herbivores, thriving across the supercontinent Pangea and frequently making up the majority of fossilized vertebrates.

These ancient reptiles had specialized feeding adaptations, including toothless beaks and rows of sharp teeth, that enabled them to process hard plant materials, making them dominant in their terrestrial ecosystems.

Paleontologist Chung Hee Schiefelbein from the Federal University of Santa Maria noted, “Rhynchosaurs are an early branch of archosauromorphs, with several species from the middle to late Triassic period, although their origins trace back to the early Triassic.”

“The Rhynchosaurs thrived across most of Pangea, with fossil records found in present-day Brazil, Argentina, Canada, the United States, Zimbabwe, Tanzania, South Africa, Madagascar, India, England, and Scotland.”

By the Late Triassic, these reptiles had achieved nearly global distribution and played a pivotal role as primary consumers in terrestrial ecosystems.

Due to their prevalence, particularly in Late Triassic formations, rhynchosaurs are also vital as biostratigraphic markers, contributing up to 90% of vertebrate fossils in some geological outcrops.

The holotype specimen of Isodapedon varsalis was excavated from the Valzea do Agudo archaeological site in Rio Grande do Sul, Brazil, dating back to the Carnian period of the Triassic, about 230 million years ago.

Unique features of the upper jaw of Isodapedon varsalis, including symmetrical teeth rare among similar species, suggest a distinct feeding strategy compared to other known rhinocosaurids.

Phylogenetic analysis indicates that Isodapedon varsalis falls outside previously recognized South American hyperodapedontins, prompting a reevaluation of the traditional classification of these reptiles and calling for a refined definition of the well-known genus Hyperodapedon.

This finding implies a more intricate evolutionary radiation of rhynchosaurs than previously thought, with closely related forms widely distributed across southwestern Gondwana in southern Pangea while maintaining a conservative body plan.

“Isodapedon varsalis presents a distinctive combination of craniomandibular traits, including symmetrical maxillary toothing and autapomorphic dental features, setting it apart from contemporary species such as Macrocephalosaurus mariensis and Hyperodapedon sp.,” the researchers emphasized.

These differences likely reflect diverse ecological strategies within herbivore guilds, indicating potential niche partitioning during the dynamic environmental and floral changes of the Carnian pluvial period.

Moreover, its similarities to early-diverging hyperodapedontins from Argentina and possibly Zimbabwe imply a widespread, morphologically stable radiation across southwestern Gondwana, underscoring ecological consistency before more derived, geographically limited lineages emerged.

An article detailing this significant discovery was published in the journal Royal Society Open Science on April 15th. For more information, check out the full paper.

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Chung Hee Schiefelbein et al. 2026. A new ceratopsian of the subfamily Hyperodapedontinidae, excavated from a cynodont-dominated site (Upper Triassic) in southern Brazil. R Soc Open Science 13 (4): 260176; doi: 10.1098/rsos.260176