Closest ancestor to dinosaurs
Pro Research Analysisby 
Searched over 200M research papers
Consensus Meter
Closest Ancestor to Dinosaurs: Insights from Recent Research
Introduction to Dinosaur Ancestry
Understanding the closest ancestors to dinosaurs involves delving into the evolutionary history of the Mesozoic Era. Recent discoveries and analyses have provided significant insights into the origins and early evolution of dinosaurs, highlighting key transitional species and evolutionary events.
Primitive Dinosaur Skeletons: Eoraptor and Early Dinosaur Evolution
One of the most pivotal discoveries in understanding dinosaur ancestry is the primitive dinosaur skeleton of Eoraptor lunensis from the Upper Triassic strata in Argentina. This species, with its heterodont dentition and bipedal posture, is considered close to the common ancestor of all dinosaurs. The anatomical features of Eoraptor suggest it is phylogenetically allied with theropods, supporting the hypothesis that dinosaurs diverged rapidly from a common ancestor at a small body size .
Miniaturization and Early Ornithodirans: Kongonaphon kely
Another significant find is Kongonaphon kely, a tiny ornithodiran from the Triassic of Madagascar. This species, estimated to be about 10 cm in height, provides evidence of a pronounced miniaturization event near the common ancestor of dinosaurs and pterosaurs. This miniaturization may have played a crucial role in the origins of flight in pterosaurs and the development of fuzzy integument in both groups. The rarity of early ornithodirans in the fossil record is likely due to their small size and taphonomic biases rather than a true reflection of their evolutionary history.
Silesaurids and Dinosauriforms: Sacisaurus and Asilisaurus
Silesaurids, such as Sacisaurus agudoensis from Brazil, are considered the closest relatives of crown-group dinosaurs. The osteohistology of Sacisaurus reveals rapid growth rates similar to early dinosaurs, although with simpler vascular patterns indicating relatively slower growth compared to most dinosaurs. Similarly, Asilisaurus kongwe from the Middle Triassic of Tanzania provides detailed anatomical data that suggest high homoplasy and parallel trends within Silesauridae and early dinosaur lineages.
Temporal Calibration and Biogeography of Dinosaur Origins
Precise temporal calibration using radioisotopic ages has shown that the gap between dinosaur precursors and the first dinosaurs was shorter than previously thought, suggesting a rapid evolutionary event. This rapid origin was not associated with a fundamental shift in ecosystem composition, indicating that dinosaurs gradually dominated terrestrial ecosystems millions of years later. Biogeographic analyses consistently support a southern Gondwanan origin for dinosaurs, with early diversification occurring in South Pangea .
Conclusion
The closest ancestors to dinosaurs include a range of early dinosauriforms and silesaurids, with significant evolutionary events such as miniaturization playing a crucial role. Discoveries like Eoraptor, Kongonaphon, Sacisaurus, and Asilisaurus provide critical insights into the anatomy, growth patterns, and biogeographic origins of early dinosaurs. These findings collectively enhance our understanding of the complex evolutionary history leading to the rise of dinosaurs.
Sources and full results
Most relevant research papers on this topic