Instead, it was a solid bony structure similar to that of the first tetrapods.

The bony structure was suffused with tiny blood vessels that would heat it to a temperature high enough to melt through the ice.

Since the bony structure and musculature was modified in this way it has remained essentially unchanged, and modern crocodilians vary little from their ancestors in this respect.

Most fish have bony structures, otoliths, which have annual growth rings, but whale sharks don't.

Bony structures are often compared to otoliths as far as accuracy.