Sharpbeak is the Land Before Time term for Ichthyornis, and possibly other birds. Sharpbeaks are shown to be carnivorous, but can usually only get small prey due to there small size.
The only Sharpbeak ever seen is Ichy, who is blue-grey, black and white. While characters in The Land Before Time often have different colours from their species, many modern seabirds have colours like this suggesting that most Sharpbeaks have this type of colouration. Ichy relied on Dil to catch him food and in turn Dil relied on his sharp eyes to find it. He lived in the Land of Mists.
Real Ichthyornis are seabirds, so they probably live near the sea and eat mainly fish in The Land Before Time. However, since only one Sharpbeak has been seen it isn't known.