SOLVED. 80's sci-fi/fantasy about a high achiever/genius/racing car driver title maybe called Emergence

[Saj]

I have been searching for this book for years having read it as a teenager I really want to see if it is as engrossing as I remember. The protagonist is a high achieving all round genius who gets transported somehow to another planet where during his adventures he is transformed into a pterodactyl! The paperback cover had a picture of the pterodactyl on it.
I think the title could be Emergence.

[Saj]

Found it?!? 🤦🏽‍♀️
It was impossible to find last time I looked a couple of years ago and just after posting this I find it within a few minutes.

It was called Threshold by David Palmer

Emergence was another ( better book) by the same author.

[Conal]

If you liked Emergence, you should read the sequel Tracking if you can find a copy (never actually released but printed in Analog magazine in 2008).

[Saj]

Thanks for the recommendation