I believe the main similarity is the cue in The Lost World where the team is walking through the long grass and gets eaten by raptors, the first minute or so of which sounds very much like a slightly slowed down version of the cue called 'The Island' from King Kong (beginning of Track 3 on the Stromberg CD).
Sorry, but there is DEFINITELY a sax at the beginning of Irina's theme, doubling the stopped horn all the way through. You can hear its distinctive timbre most prominently on the G#-A at the very beginning (ie the second and third notes of the theme) and especially the two B flats at 00:22. After that latter moment, the horn becomes more prominent, but it's certainly there still.
Funnily enough, the opening sort of reminded me a little bit of the beginning of John Adams's El Dorado, albeit a much faster and more frenetic version of the latter. I suppose that connection is appropriate for this film...
I must also strongly disagree about Secret Doors and Scorpions being boring; I think it's a fantastic track! 00:32 to 00:43 especially is one of the few bits that sounds to me as if it could have come straight out of The Last Crusade, and then there's some great bass clarinet/bassoon writing just after it. But my favourite bit of the whole track is the amazing horn bit at 01:24, underscoring the opening of the secret door; that's just a great moment that I enjoy playing over and over again! I really, really like those few seconds!