« "The thin, lime coloured crest on its head opening and closing like a Chinese fan, his long green body swaying from side to side as his transparent wings stuck firmely on his sides." »
— Description[src]

Coelurosauravus were small, lizard-like diapsid reptiles, native to the Permian period which resembled green iguanas or other modern day lizards. It had specialised wing-like structures allowing it to glide, similarly to the modern day Flying Dragon from South-east Asia.


Coelurosauravus were approximately the same size as a human arm but slightly larger, with a long, streamlined body resembling that of some modern lizards. Coelurosauravus' body possessed two large, wing-like structures, which allowed it to achieve powered flight and gliding around its environment in the air. Due to the arid Permian climate of their home time, Coelurosauravus would be unused to the modern day's cooler, seasonal climate and preferred high temperatures, and were dangerously vulnerable to freezing temperatures.


Rex almost freezes in a fridge's cold temperatures. (Episode 2.4)

Coelurosauravus appeared to live in small flocks together in their home time, although some of them could be more solitary or stray off. They also communicated with varying chirping vocalisations, and they apparently had an unusually long memory span for reptiles (over a year at least). Despite Coelurosauravus being cold-blooded reptiles, at least one, Rex, was shown to be unusually active, intelligent and curious; although it is unknown if this is a common characteristic for Coelurosauravus or if Rex's behaviour was atypical.

Known Coelurosauravus


A flock of Coelurosauravus in their Permian home. (Episode 1.1)

Real life

Coelurosauravus (name meaning "Hollow lizard grandfather") was a basal diapsid reptile genus, which was 30-50 cm in length approx. It lived in what is now Madagascar, England and Germany, during the Upper Permian period. Coelurosauravus possessed wing-like structures (dermal bones with skin stretched over them) and a long and flat body, allowing it to glide.





  • Coelurosauravus is the first creature to be given a name, and one of the few creatures to actually be given one.
  • This is the only creature to appear in all five series of the original Primeval show.
  • As the series continues Rex's wings become more dragon/bat like, starting as rounded sails and then progressing into folding wings similar to a bat's.
  • A flock of Coelurosauravus were featured on the Series 1 and Series 2 title sequences.


  • Real Coelurosauravus were only capable of gliding, but the ones in the show were capable of powered flight.
  • The crest on Coelurosauravus' heads is speculative, and they aren't depicted with the distinctive bony frill that the real ones had.
  • It is depicted as being much larger than the real animal, which was only about as long as a human hand.
  • Rex seems to be far more intelligent and active than a primitive reptile would probably have been. However, Rex could just be an unusual specimen.
  • Rex is often shown being fed plant and fruit matter, but Coelurosauravus was probably an insectivore.

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