Paleontologists in Brazil have discovered fossilized remains of a remarkably small sauropodomorph dinosaur, offering new clues about the growth and development of these early relatives of the giant long-necked dinosaurs. The find, detailed in the April 2026 issue of the journal Palaeoworld, centers on bones unearthed from the Cerro da Alemoa outcrop in southern Brazil’s Rio Grande do Sul state.
The fossils, dating back to the Carnian age of the Late Triassic period – between 237 and 227 million years ago – consist of several tiny bones, none exceeding 5.7 centimeters (2.2 inches) in length. These include a partial humerus, a metatarsal, an ungual phalanx, a neural arch, and a vertebral centrum. Researchers, led by Dr. Luciano Artemio Leal from the Universidade Estadual do Sudoeste da Bahia, determined through phylogenetic and anatomical analyses that the specimen represents a basal sauropodomorph.
“The specimen is an important juvenile dinosaur,” the paleontologists stated in their research. Their combined analysis of the fossil’s morphology, bone microstructure, and evolutionary relationships confirms its place as a primitive sauropodomorph from the Brazilian Triassic. Unlike the massive sauropodomorphs that would later dominate the Jurassic and Cretaceous periods, this individual was still growing when it died.
A key aspect of the discovery lies in the bone microstructure. Analysis revealed evidence of at least one complete growth interruption, indicated by a distinct line of arrested growth within the bone tissue. This suggests the young dinosaur experienced a pause in its development. Researchers believe the individual was midway through its second growth cycle at the time of its death.
“These analyses suggest ontogenetic features of a juvenile sauropodomorph with a single growth arrest,” the research team wrote. This pattern of interrupted growth is significant since it suggests that even relatively small sauropodomorphs employed flexible growth strategies. Scientists hypothesize that this adaptability may have been a precursor to the eventual evolution of gigantism within the group. The findings indicate that early sauropodomorphs were experimenting with different growth patterns, potentially laying the groundwork for the immense sizes seen in later species.
The Cerro da Alemoa outcrop, where the fossils were found, is recognized as a crucial geological and paleontological site within the Santa Maria Supersequence in central Rio Grande do Sul, according to the researchers. The discovery adds to the growing body of evidence about dinosaur evolution in South America during the Triassic period.
The research was published under the title “A new tiny basal Sauropodomorpha (Dinosauria: Saurischia) from the Santa Maria Supersequence, Upper Triassic of southern Brazil” with the doi: 10.1016/j.palwor.2025.201064.