Carmel Church fish weirdness

This is more of the fallout from our Dino Day rush of prep work on Carmel Church specimens. For some years we’ve been finding small numbers of bony fish vertebrae like the one shown above.

They consist of a series of bony struts, and are mostly open through the middle of the bone. They’re quite different from most of the fish vertebrae we find, which also have the bone struts but are solid through the middle, as shown in the vertebra below (six views of one specimen):

For a long time I thought that the airy, strut vertebrae were just normal vertebrae that had been eroded and damaged. I’ve gradually come to believe that they are not damaged at all, but are actually well preserved. In part this is because we’ve found several of them now, and in part it’s because they include quite delicate structures that should have been lost if the bone was eroded either chemically or mechanically.

So, given that the structure of these vertebrae seems to be real (rather than a taphonomic artifact), what kind of fish do they represent? Presumably they belong to some type of fish in which the vertebral column doesn’t completely ossify, but still an osteichthyan (bony fish), as sharks have a completely different vertebral structure. Ocean sunfish famously have poorly ossified skeletons, and are already known from Carmel Church, so that might be a possibility. Are there other candidates?

Anyone have any suggestions?

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4 Responses to Carmel Church fish weirdness

  1. boesse says:

    Hey Butch,

    The bottom vert appears to be Thunnus or something similar; the vert in the top picture bears some resemblances with Paralichthys, or at least flatfish/flounders in general (i.e. the dendritic, branching pattern of the septae on the bony laminae). From the little work I’ve done trying to ID fish vertebrae on my end, Thunnus (and Scombrids in general) is characterized by rather convex, smooth lamina. The possibility remains that the weird vertebra could have been digested; but I’d expect perhaps a different pattern of dissolution (i.e. eroded extremities of bones, rather than the middle of the bone).

    In any event… that certainly does qualify as ‘weirdness’ in my book…

  2. Alton Dooley says:

    The pattern of preservation is what has led me to think these are not taphonomic features. As you say, the delicate parts of the bone are preserved and the more robust parts have been lost.

    I hadn’t looked at flatfishes yet. This vertebra is almost 4 cm long, so it’s from a good-sized fish. But, looking at Fishbase, I see that P. olivaceus is known to reach 103 cm in length, and has 38 vertebrae. That would actually make the largest vertebrae about this size.

    I had been leaning toward a scombrid for the lower vertebra, mainly because it’s huge (not the scale bar). It’s actually as big as the thoracic vertebrae from Diorocetus! It doesn’t really look like a marlin, so that doesn’t leave a whole lot of other options for a fish this size; tuna and groupers were looking like the best bets.

  3. Grenda says:

    What advantage would this type of structure give to a fish? Would this enable it to jump out of the water easier? Like a sailfish or marlin? Make it swim faster? What? I may have the advantage here of nothing absolutely nothing? Then again….

  4. Alton Dooley says:

    It doesn’t necessarily have to confer an advantage, just not result in a disadvantage. That said, there are potential advantages in reducing the skeleton: lighter weight, increased flexibility. Developmental factors could also come into play. There could be some advantageous feature that develops in such a way that the skeleton is reduced as a side effect. This sort of thing is implicated in the loss of eyes in cave-dwelling animals, for instance.

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