The rumors are there are. Beaides, Nublar had miles of underground tunnels. At the very least, smaller dinosaurs survived down there.

EDIT- I found this on deviantArt.

[hider=D. Rex official?][img]http://fc08.deviantart.net/fs70/f/2014/331/5/c/the_diabolus_rex___by_sonichedgehog2-d87wdn2.jpg[/img][/hider]