Avalonianus was a type of ancient reptile that lived during the Late Triassic period, around 210 million years ago. It was found in what is now England, specifically in the Westbury Formation.
The first scientific description of Avalonianus was made by a paleontologist named Harry Seeley in 1898. He originally called it Avalonia, but that name was already used for another group, so it had to be changed. In 1961, a scientist named Oskar Kuhn renamed it Avalonianus.
There is still much debate about Avalonianus. At first, it was believed to be a type of prosauropod, which are early relatives of sauropod dinosaurs like the famous Brachiosaurus. However, further studies showed that it might not be a true dinosaur. The teeth associated with Avalonianus likely came from a different group of reptiles instead.
The remains we have from Avalonianus mostly consist of fossilized teeth, but many of these fossils have been lost over time. Because of this uncertainty and the mix of different types of remains, scientists consider Avalonianus to be dubious, or questionable, as a separate genus.
In summary, Avalonianus is an interesting but unclear part of dinosaur history, showing how complex and varied ancient life can be.