Macrocollum itaquii
Macrocollum itaquii was a slender, two-legged plant-eater that reached roughly 3 to 3.5 metres in length and weighed an estimated 60 to 110 kilograms. Its most striking feature is the one that gave it its name: Macrocollum means "long neck".
Macrocollum
Macrocollum itaquii
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Weight
60–110 kg
Length
3–3.5 m
Diet
Herbivore
Period
Triassic
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60–110 kg
3–3.5 m
Triassic
Bipedal
0.8–1.5 m
Herbivore
2 recorded fossil finds in Brazil. First described in 2018 by Müller et al..
Sites and counts from the Paleobiology Database
The timeline shows the whole age of dinosaurs – and how much time has passed since. The glowing part is when Macrocollum lived.
million years ago
Lived 227–225 million years ago
If the whole age of dinosaurs were a single day, Macrocollum lived at 03:21.
Chapter • Meet the dinosaur
Macrocollum itaquii was a slender, two-legged plant-eater that reached roughly 3 to 3.5 metres in length and weighed an estimated 60 to 110 kilograms. Its most striking feature is the one that gave it its name: Macrocollum means "long neck". The neck vertebrae are markedly elongated, giving the animal a neck that is proportionally longer relative to its body than in any other known Triassic dinosaur. The head was small and low, equipped with leaf-shaped, coarsely serrated teeth suited to cropping plant material, while the long hind limbs and lightly built forequarters show that it walked and ran bipedally. The tail was held out horizontally as a counterweight rather than dragged along the ground. There is no evidence for feathers or feather-like structures in early sauropodomorphs such as Macrocollum, so it is reconstructed with scaly skin.
Chapter • Where it lived
Macrocollum lived in the Late Triassic (Norian stage), roughly 225–227 million years ago, in what is now the state of Rio Grande do Sul in southern Brazil. The specimens come from the Wachholz site near the town of Agudo, in rocks of the Candelária Sequence within the Santa Maria Supersequence. The setting was a broad inland floodplain deep inside the supercontinent Pangaea, crossed by seasonal rivers and marked by a semi-arid, strongly seasonal climate. Conifer-like plants, ginkgophytes, ferns and horsetails grew there, and Macrocollum shared the landscape with early predatory dinosaurs, large carnivorous archosaurs and herbivorous rhynchosaurs.
Chapter • Wild behavior
Diurnal
The three Macrocollum skeletons were recovered side by side in the same layer, partly preserved in similar postures. Many researchers read this as evidence that the animals died at the same time and lived together, which would make it one of the oldest known indications of gregarious behaviour in dinosaurs. The interpretation is not certain, however: the bodies could also have been gathered by water after death. Whether these animals cared for young together, or had any more permanent social structure, remains unknown.
The genus name combines Greek makros (long) with Latin collum (neck); the species name itaquii honours José Jerônimo Itaqui for his work on education and heritage in Rio Grande do Sul.
Macrocollum is one of the earliest dinosaurs known to have a clearly elongated neck – an early step towards the towering necks of later sauropods.
Three nearly complete skeletons were found together in the same bed, one of the oldest hints that dinosaurs could live in groups.
The fossils come from the Wachholz site near Agudo in southern Brazil and are radiometrically dated to about 225 million years ago.
At around 3–3.5 metres, Macrocollum was noticeably larger than the very oldest sauropodomorphs such as Buriolestes, which measured only about two metres.
Although it sits on the sauropod branch of the family tree, Macrocollum walked on two legs; the four-legged giants appeared much later.
It belongs to the family Unaysauridae, together with Unaysaurus from Brazil and Jaklapallisaurus from India.
The small skull and leaf-shaped teeth point to a plant diet, but several researchers argue that the earliest sauropodomorphs may have been more omnivorous than their gigantic descendants.
Chapter • Scientific place
Biology Letters (The Royal Society)
Reviewed: 9/8/2026
Original description of Macrocollum itaquii, erecting the species and placing it within Dinosauria, Saurischia, Sauropodomorpha, Unaysauridae.
Open sourceHistorical Biology
Reviewed: 9/8/2026
Documents the known fossil localities of the species in Rio Grande do Sul, Brazil, and its stratigraphic distribution within the Candelária Sequence.
Open sourceJournal of South American Earth Sciences
Reviewed: 9/8/2026
Describes the sedimentology, taphonomy and palaeoenvironment of the Wachholz site near Agudo, the type locality of Macrocollum.
Open sourceJournal of Systematic Palaeontology
Reviewed: 9/8/2026
Detailed description of the skull, jaws and dentition, the anatomical basis for inferring a herbivorous/plant-dominated diet in this early sauropodomorph.
Open sourceHistorical Biology
Reviewed: 9/8/2026
Extinct taxon; conservation status NE
Open sourceBiology Letters (The Royal Society)
Reviewed: 9/8/2026
Peer-reviewed overview of the species based on three nearly complete skeletons, covering age, anatomy, neck elongation and evolutionary significance.
Open sourceBiology Letters (The Royal Society)
Reviewed: 9/8/2026
Peer-reviewed overview of the species based on three nearly complete skeletons, covering age, anatomy, neck elongation and evolutionary significance.
Open sourceBiology Letters (The Royal Society)
Reviewed: 9/8/2026
Peer-reviewed overview of the species based on three nearly complete skeletons, covering age, anatomy, neck elongation and evolutionary significance.
Open sourceBiology Letters (The Royal Society)
Reviewed: 9/8/2026
Peer-reviewed overview of the species based on three nearly complete skeletons, covering age, anatomy, neck elongation and evolutionary significance.
Open source