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The dinosauroid is a hypothetical species created by Dale A. Russell in 1982. Russell theorized that if a dinosaur such as Stenonychosaurus did not perish in the Cretaceous–Paleogene extinction event, its ancestors may have evolved to fill the same ecological niche as humans. While the theory has been met with criticism from other scientists, the dinosauroid has been featured widely in books and documentaries since the theory's inception.

Theory

In 1982, Dale A. Russell, then curator of vertebrate fossils at the National Museum of Canada in Ottawa, conjectured a possible evolutionary path for Stenonychosaurus, if it had not perished in the Cretaceous–Paleogene extinction event, suggesting that it could have evolved into intelligent beings similar in body plan to humans. Over geologic time, Russell noted that there had been a steady increase in the encephalization quotient or EQ (the relative brain weight when compared to other species with the same body weight) among the dinosaurs. Russell had discovered the first Troodontid skull, and noted that, while its EQ was low compared to humans, it was six times higher than that of other dinosaurs. Russell suggested that if the trend in Stenonychosaurus evolution had continued to the present, its brain case could by now measure 1,100 cm³, comparable to that of a human.

Troodontids had semi-manipulative fingers, able to grasp and hold objects to a certain degree, and binocular vision. Russell proposed that his dinosauroid, like members of the troodontid family, would have had large eyes and three fingers on each hand, one of which would have been partially opposed. Russell also speculated that the dinosauroid would have had a toothless beak. As with most modern reptiles (and birds), he conceived of its genitalia as internal. Russell speculated that it would have required a navel, as a placenta aids the development of a large brain case. However, it would not have possessed mammary glands, and would have fed its young, as some birds do, on regurgitated food. He speculated that its language would have sounded somewhat like bird song.

Head and neck of Dale Russell and Ron Seguin's Stenonychosaurus sculpture, Natural History Museum, London

Reflecting on the dinosauroid theory, Russel said in an interview in 2000;

"The 'dinosauroid' was a thought experiment, based on an observable, general trend toward larger relative brain size in terrestrial vertebrates through geologic time, and the energetic efficiency of an upright posture in slow-moving, bipedal animals. It seems to me that such speculation remains acceptable, particularly if directed toward non-anthropoid anatomical configurations. However, I very nearly decided not to publish the exercise because of the damaging effects it might have had on the credibility of my work in general. Most people remained polite, although there were hostile reactions from those with 'ultra-quantitative' and 'ultra-intuitive' world views."

The theory, perhaps due to its outlandish premise and the dinosauroid's striking image, became a staple in dinosaur books published throughout the 1980s and into the 2000s.

Sculpture

Dale Russell worked in collaboration with taxidermist and artist Ron Seguin to create models of both a Stenonychosaurus and the fictional dinosauroid. While the model of Stenonychosaurus was constructed to reflect the biology of Stenonychosaurus as accuratley as possible, the dinosauroid was wholly fabricated. The models were made in tandem using similar techniques, the Stenonychosaurus model taking about seven months to construct and the dinosauroid model taking about three and a half months to construct. The two models were built using similar tecniques, built up over a skeleton of the creature, the final sculpt then being recast in fiberglass and filled with sand.

It can be assumed Seguin's sculpture depicts a male dinosauroid since Russell theorized males of the species could possibly posses a wattle underneath their chin.

Reception

Russell's thought experiment has been met with criticism from other paleontologists since the 1980s, many of whom point out that his Dinosauroid is overly anthropomorphic. Gregory S. Paul (1988) and Thomas R. Holtz, Jr., consider it "suspiciously human" and Darren Naish has argued that a large-brained, highly intelligent troodontid would retain a more standard theropod body plan, with a horizontal posture and long tail, and would probably manipulate objects with the snout and feet in the manner of a bird, rather than with human-like "hands".

As Darren Naish explained in a 2012 Scientific American article on the subject of the dinosauroid,

"The reason that we humans have the body shape that we do is not - I think - because it's the 'best' body shape for a smart, big-brained biped to have, it is instead the result of our specific lineage's evolutionary history. Given that, so far as we know, the humanoid body shape has evolved just once, we simply have no way of knowing whether it's a particularly 'good' morphology or not."

Some authors, however, had more favourable opinions on the dinosauroid, with David Norman remarking in the 1985 book The Illustrated Encyclopedia of Dinosaurs that “Such an idea is an obviously fanciful, though provocative thought.”

A replica of Ron Seguin's Dinosauroid sculpture on display at The Dinosaur Museum, Dorchester, in 2009

The dinosauroid theory, along with the often repeated fact that Troodontids were the most intelligent dinosaurs, may have lead to an overestimation of its intelligence among the general public; while Stenonychosaurus did have a larger brain to body ratio when compared to other theropod dinosaurs of its time, its intelligence was likely comparable to that of modern birds such as bustards and emus.

In popular culture

• In a 1984 Animal Kingdom magazine article titled "Evolutionary Bioparanoia", paleontologist John C. McLoughlin created an alternate imagining of Russell's dinosauroid. Dubbed "Bioparaptor macloughlini" by Darren Naish, McLoughlin's anthropomorphic dinosaur was a highly intelligent derivative of Deinonychosaurs, and was proficient in agriculture, raising Ceratopian livestock to the point of environmental degradation. The article would go on to explain that the intelligent Deinonychosaurs caused their own extinction via a deadly nuclear conflict, which modern paleontologists interpret as the Cretaceous–Paleogene extinction event.
• The 2007 children's show Dinosapien includes dinosaurs that have survived into the modern day and gained human-like intelligence, with the character Eno somewhat resembling Russell's Dinosauroid.
• The 2015 Pixar film The Good Dinosaur is built upon a similar premise of dinosaurs developing human-level intelligence in the absence of a mass extinction.
• Season 4, episode 11 of the children's show Dino Dana (17 April 2020) centers around the theory that Stenonychosaurus could have possibly evolved into a "dinosauroid".

See also

• Speculative evolution
• The New Dinosaurs
• Reptilian humanoid