Small Triassic Dinosaur from Brazil Sheds New Light on Sauropodomorph Growth Strategies
Paleontologists have unearthed fossilized bones of one of the smallest sauropodomorph dinosaurs from the Late Triassic of southern Brazil, providing new insight into the development and physiology of early dinosaurs.
Massospondylus carinatusa species of small sauropodomorph dinosaur from the Lower Jurassic of southern Africa. Image credit: Nobu Tamura, http://spinops.blogspot.com/Patty Jansen/Sci.News.
Dr. Luciano Artemio Leal from the Universidade Estadual do Sudoeste da Bahia and his colleagues collected the new dinosaur material from the Cerro da Alemoa outcrop in southern Brazil.
“The Cerro da Alemoa outcrop is an important geological and faunal record of the Santa Maria supersequence in the central part of the state of Rio Grande do Sul,” they explained.
The material dates from the Carnian age of the Late Triassic Epoch, between 237 and 227 million years ago.
It is made up of tiny bones, all less than 5.7 cm (2.2 inches) in length, including a partial humerus, metatarsal, nail phalanx, neural arch, and vertebral centrum.
Phylogenetic and anatomical analyzes conducted by the team place the specimen firmly within the basal sauropodomorph clade.
“The specimen is an important juvenile dinosaur,” the paleontologists said.
“A combined analysis of its morphology, osteohistology and phylogeny positions it as a basal sauropodomorph from the Brazilian Triassic period.”
Unlike later sauropodomorphs which reached enormous body sizes, this early form appears to have had a much smaller stature while still developing.
Importantly, the bone microstructure reveals evidence of at least one complete cycle of growth arrest with a line of growth arrest, suggesting that the individual experienced pauses in development early in life.
This trend indicates that even with small bodies, early sauropodomorphs may have adopted flexible growth strategies – a finding that could help explain the later emergence of gigantism in this group.
“The observed characteristics suggest that this is an individual still developing, having already undergone its first growth arrest and being midway through its second cycle,” the researchers said.
“These analyzes suggest ontogenetic characteristics of a juvenile sauropodomorph with a single growth arrest.”
“Our results provide evidence for novel growth strategies during the early evolution of this group, leading to the emergence of small-bodied dinosaurs in the Triassic.”
The results will be published in the April 2026 issue of the journal Paleoworld.
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Leomir Santos Campos and others. 2026. A new small basal Sauropodomorpha (Dinosauria: Saurischia) from the Santa Maria supersequence, Late Triassic of southern Brazil. Paleoworld 35 (2): 201064; doi: 10.1016/j.palwor.2025.201064
