When people think of dinosaurs, images of colossal creatures often come to mind. The sheer scale of animals like the massive, long-necked sauropods can overshadow the fact that the dinosaur family was incredibly diverse in size. For every giant that shook the prehistoric world, there were smaller, more delicate species navigating life at a completely different scale. Uncovering the smallest of these ancient reptiles reveals a fascinating and often-debated corner of paleontology.
The Current Smallest Known Dinosaur
Pinpointing the smallest dinosaur is a challenge, as it can be difficult to determine if a fossil belonged to a fully-grown adult or a juvenile. However, several contenders have emerged. Among the smallest non-avian dinosaurs known from adult specimens is Parvicursor remotus, a slender animal from the Late Cretaceous. Its name, meaning “small runner,” hints at its build, with long legs adapted for speed.
Fossil evidence of Parvicursor has been found in Mongolia, where scientists estimate it measured about 39 centimeters (15 inches) long and weighed 162 grams. Another small dinosaur was Compsognathus longipes, from Europe’s Late Jurassic period. For a long time, Compsognathus was considered the smallest dinosaur; its body was chicken-sized, but a long tail brought its total length to about a meter (3 feet).
Other tiny dinosaurs include species like Epidexipteryx hui, which lived in China during the Jurassic period. This creature was about 25 to 30 centimeters (9.8 to 11 inches) long, not including its distinctive long tail feathers, and weighed an estimated 164 grams. Another small, feathered dinosaur from China is Anchiornis huxleyi, which was about 34-40 centimeters long and weighed around 110 grams.
A Famous Contender and Scientific Debate
The search for the smallest dinosaur changed in 2020 with the announcement of a fossil discovery. Preserved in 99-million-year-old Burmese amber was a tiny, bird-like skull. The creature, named Oculudentavis khaungraae, was described as comparable in size to the bee hummingbird, making it the smallest dinosaur then believed to be found. The initial study highlighted its dinosaur-like features, capturing global attention.
The skull of Oculudentavis was just over 1.5 centimeters long, and its features seemed to blend bird and dinosaur characteristics. It had a large eye socket with a ring of bones, similar to some birds, but it also possessed a jaw filled with numerous sharp teeth, suggesting a predatory lifestyle. The initial researchers proposed it was a primitive bird-like dinosaur, offering a glimpse into the evolution of miniaturization as dinosaurs evolved into modern birds.
This conclusion, however, was soon met with skepticism from other paleontologists. Researchers pointed out features more consistent with lizards than dinosaurs, for example, the way the teeth were attached to the jaw and the shape of certain skull bones were more typical of squamates (the group that includes lizards and snakes). A more complete specimen found later confirmed these suspicions, showing a distinctly lizard-like body plan. This led to the retraction of the original paper and the reclassification of Oculudentavis as a peculiar type of ancient lizard.
Lifestyle of a Miniature Dinosaur
The life of a miniature dinosaur was different from its gigantic relatives. Fossil evidence shows these small animals were active and agile predators. The sharp teeth of Compsognathus suggest they hunted small prey. Fossilized remains of small lizards have been found in the stomach cavities of Compsognathus specimens, providing direct evidence of their diet.
With their small stature, they would have been prey for a wide range of larger carnivorous dinosaurs, as well as other predators like pterosaurs and crocodiles. Their survival likely depended on speed and keen senses. This agility would have been used for chasing down insects and other small invertebrates while also evading danger.
The environments these small dinosaurs lived in were lush and varied, from tropical archipelagos to forests. Feathered dinosaurs like Anchiornis and Epidexipteryx had plumage that may have been used for insulation or display, similar to modern birds. While they may not have been capable of powered flight, their feathers could have assisted in gliding between trees to hunt insects and escape ground-based threats.