Where Are They?

[TyrannosaurusRex]

My hunting grounds are close to Big Lake tx. There is something in the ecosystem that I just cannot wrap my head around. There is an incredibly rich source of shells including oysters, gastropods and other miscellaneous shells. There are urchins, giant clams, crab, shrimp and ammonites. There are brachiopods, there is fossilized cracked earth. Where are the predators? Where are the fish? There is a huge gap missing and I want to know if they just didnt fossilize or if they were never there. If you know anything I would appreciate knowing what you think.

[TyrannosaurusRex]

Also the place I find the is a caliche pit.

[Auspex]

Since the missing predators you are looking for are vertebrates (remember that some snails, crabs, shrimp, and ammonites are predators), I suspect that a preservational bias is at work. Calcite, aragonite, and chiton seem to be preserved, but maybe not the phosphate materials?

[TyrannosaurusRex]

Since the missing predators you are looking for are vertebrates (remember that some snails, crabs, shrimp, and ammonites are predators), I suspect that a preservational bias is at work. Calcite, aragonite, and chiton seem to be preserved, but maybe not the phosphate materials?

Do you know what marine reptiles could have been there? Edited February 4, 2015 by TyrannosaurusRex

[PFOOLEY]

I have questioned this many times in my scouring the Puerco...all this marine life, yet no marine reptiles. There is a lot of seaway regression and transgression exposed in these outcrops...maybe that plays a part.

I don't doubt they were here, just haven't found their remains yet.

[Kosmoceras]

I am not aware of your site or what sort of environment it was so I can’t give any definite answer for your site in particular. Whether the environment was a lake, an estuary, a shallow sea, a deep sea and the type of deposition etc are all important factors to be noted before conclusion. Nonetheless, ecosystems run off some basic principles.

A lot of energy is lost every time you venture up a trophic level in an ecosystem (around 90%), so there must be a tonne biomass to support a single large predator. So naturally there have to be far fewer predators than prey groups. If your hunting site is from an environment which could support these species (highly likely), then they will be there, just much less common than the invertebrate fauna. Remember, not all ecosystems have a vertebrate predator. They could be absent due to the type of environment - it might not have been suitable for these species to adapt.

It could also just be that your site is not a large enough exposure to allow you to be regularly finding vertebrates. As said before, keep looking.

[erose]

As stated by others they were there but in such smaller numbers compared to the other critters that they are slim in the fossil record. A great example here in Texas is the Glen Rose Formation (Albian, Lower Cretaceous) which is a really thick formation that covers a huge area and in places is loaded with marine invertebrates. And all through it's range we can find dinosaur footprints in the shallowest deposits where they roamed the shorelines. But bones of those dinos are few and far between. In my own years of collecting the Glen Rose I have found maybe six shark or fish teeth and a smattering of bones (probably fish & turtle) in amongst the shells and other invertebrates.