The discovery of fossilized skeletal fragments belonging to one of the most diminutive sauropodomorph dinosaurs, originating from the Late Triassic period in southern Brazil, is furnishing novel perspectives on the nascent stages of dinosaur evolution and their physiological characteristics.
Massospondylus carinatus, a species of small sauropodomorph dinosaur from the Early Jurassic of southern Africa. Image credit: Nobu Tamura, http://spinops.blogspot.com / Patty Jansen / Sci.News.
A team spearheaded by Dr. Luciano Artemio Leal of the Universidade Estadual do Sudoeste da Bahia has retrieved the aforementioned dinosaurian remains from the Cerro da Alemoa geological formation situated in the southern Brazilian region.
“The Cerro da Alemoa exposure represents a crucial stratigraphic and faunal archive of the Santa Maria Supersequence within the central expanse of Rio Grande do Sul state,” the researchers elucidated.
The geological strata from which this material was extracted date back to the Carnian stage of the Late Triassic epoch, approximately 237 to 227 million years in the past.
Comprising minuscule osseous elements, none exceeding 5.7 cm (2.2 inches) in length, the collection includes a partial humerus, a metatarsal bone, an ungual phalanx, a neural arch, and a vertebral centrum.
Through meticulous phylogenetic and anatomical assessments, the research group has definitively positioned this specimen within the foundational clade of sauropodomorphs.
“This particular fossil constitutes a significant juvenile specimen of a dinosaur,” the paleontological experts stated.
“An integrated examination of its morphological attributes, osteohistological characteristics, and phylogenetic relatedness classifies it as an early-diverging sauropodomorph from Brazil’s Triassic era.”
In contrast to their later counterparts that attained immense bodily proportions, this ancestral lineage appears to have maintained a considerably more modest physique during its developmental stages.
Significantly, the internal bone structure exhibits clear indications of at least one completed growth hiatus, identifiable by a line of arrested growth (LAG), thereby suggesting that the individual organism experienced developmental pauses early in its ontogeny.
This observation implies that even at reduced body sizes, primitive sauropodomorphs might have employed adaptable growth strategies—a revelation that could potentially elucidate the subsequent emergence of gigantism within this dinosaurian lineage.
“The observed traits suggest an organism still undergoing maturation, having already passed through its initial growth arrest and being halfway through its subsequent growth phase,” the investigators commented.
“These analytical findings indicate ontogenetic traits characteristic of a juvenile sauropodomorph that experienced a singular growth interruption.”
“Our findings substantiate the presence of novel developmental strategies during the initial evolutionary trajectory of this group, which ultimately paved the way for the appearance of small-bodied dinosaurs in the Triassic period.”
These groundbreaking discoveries are slated for publication in the April 2026 edition of the esteemed journal Palaeoworld.
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Leomir Santos Campos et al. 2026. A new tiny basal Sauropodomorpha (Dinosauria: Saurischia) from the Santa Maria Supersequence, Upper Triassic of southern Brazil. Palaeoworld 35 (2): 201064; doi: 10.1016/j.palwor.2025.201064
