Thank you for your help and interest in identifing this specimen!!
(photos and responses at bottom of this page)

Description of specimen and location (to the best of my faulty memory) :

I picked up this neat stone years ago and, sadly, my memory of the EXACT location has faded. My husband and I were on a run (i.e. NO rock collecting allowed!) down a canyon, so I was speed-collecting and did not examine the location. At the time I thought it was merely a curiously dried piece of clay.

I believe it came from Crack canyon, which is in the San Rafael Reef along the eastern San Rafael Swell in Utah, about 15 miles south of interstate 70 and about 8 miles west of Utah highway 24. It may also have come from a canyon in the same reef section between there and the interstate highway. I think it was a loose flake sitting on top of an outcrop near the canyon floor (i.e. part of the canyon wall rock, not the debris on the canyon bottom). I'm sure all of you are familiar with this region, but if not, it is an area of sedimentary rock, some of it fossiliferous, primarily sandstone. This would have been a red rock layer, in the middle of the reef and toward the eastern edge.

The underside of the flake shows thin concentric rings and has a slightly curved surface which matched the larger rock surface below it. I did not look at this large rock closely (we were running and rock collecting wasn't supposed to be part of the picture), but it did not have any apparant pattern or irregularity.

The upper side is patterned and appears to have hollow pores, at least around some of the edges. The raised pattern appears to be rock, not hardened clay.

The rock appears to be a very fine-grained sandstone, or perhaps something like siltstone. It is a reddish-tan, and is about 2" x 2", an 1/8 inch thick and slightly curved. The heart shape is natural, not a chip out of a round. Please Note : the photo was taken without flash and has a greenish tone - the background paper should be white.

Here are the ideas thus far :

Answer One : "That stone you are trying to identify looks to be a "growth plate" of a vertebra of some sort. We occasionally see similar types of things with whale vertebra - given its location and size, it's probably reptilian." - - - C. B.

Answer Two : "Nice fossil whale vertebra! (Or some other aquatic mammal, or reptile (Mososaur?)). I'm an east coast invertebrate paleo. guy so I can't be much more help. It is very nicely preserved. " - - - S. P.

Answer Three : "This is an epiphysis from a vertebra (or a vertebral disk in more common terms). I don't know for sure what kind of mammal it is from, but depending on the age of the formation and assuming it is from a marine environment, it could be from a whale or sirenian. I have seen several that look almost identical to these in the coastal S.C. Oligocene marine formations. It really looks similar to one from a dugong. As the mammal grows the epiphysis is not fused onto the end of the vertebra, but once the animal has reached full maturity, it fuses onto the vertebra." - - - Anon. from Paleontology List.

Answer Four : "First of all it is an epiphysis, the face of a vertebrae. (Check my spelling as I am a notoriously poor speller). We see these a lot in Tertiary and Quaternary deposits. Usually these can separate from the main body of the vertebra if the individual was not yet an adult. In this case the vertebra was still growing and the space between the main body of the vertebra and the face was cartilege and had not fully fused. The shape is distinctive. The one group of mammals I know of that have such distinctively heart shaped vertebra are sea cows and dugongs. If it is I wonder how it got to Utah. Perhaps someone else on the list has an idea of what else it could be." - - - D. from Paleontology List.

Answer Five : "Regarding your fossil, I'm familiar with Goblin Valley area and Temple Mountain---have poked around there some myself. From your description, it sounds to me like your white layer may have been in the Carmel Formation, which immediately overlies the Navajo Sandstone, which forms most of the spectacular slot canyons in the area. The Navano Sandstone represents ancient sand dunes, perhaps somewhat like the present Sahara desert, and would not have had that sort of fossils. The overlying Carmel contains shallow marine beds, but is not normally thought of as fossiliferous. The Carmel and Navajo are both Jurassic. The other possibility might be the Kayenta Formation, which underlies the Navajo Sandstone and consists of thin red sandstones and shales, that sometimes have dinosaur footprints---but not known to contain actual bone fossils as far as I know. If you could recollect more closely where you found it, I suspect some of the paleontologists in Utah (at Univ.of Utah or Brigham Young University might be very interested. " - - - G. M.

Continuation : To answer your question, yes the age of the rock in the area would preclude large, aquatic mammals like whales, dugong (you might say "DUGONG IT !!!"). So it may be from a Mosasaur or dinosaur. Nature tends to reuse some basic architecture (convergent evolution) so what evolves in two distant groups can be morpholgically very similar (eye of a squid, eye of a human). - - - S.P.

Thanks everyone! More responses are welcome!

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