Several weeks ago I had the chance to go digging around in the Tropic Shale for Cretaceous fossils and came back with a pretty good haul of shells, snails, and ammonites. Today I got to visit another area in the Tropic and came back with more cool stuff! In this first image are two shark teeth along with one from a ray. The shark tooth on the right measures over 3 cm. (1.18 in.) and is the largest of the 36 I collected - most of them only about .64 cm. (about 1/4 in.). The ray tooth is about 1.5 cm. ( 0.6 in.) and the largest of 7 that I found.

These are pretty cool, too: Fossilized jawbones fragments from some kind of fish from the period. The smaller fragment still contains a tooth and, in the larger fragment you can see where the teeth have broken off when looking at it from the top.

Unlike my last "expedition" where it was sometimes necessary to use a rock hammer to break apart pieces of rock, this time all I did was look around on the ground (on my hands and knees!). Once I knew what I was looking for, the teeth would really stand out against the normal rock. It wasn't like they were just lying around for the taking, either, as it did require some diligent searching. Included in the day's take were some assorted fish bone fragments and a vertebrae as well as a few pieces of coprolites (that would be fossilized, um, fish poop), and some pieces of sandstone with ammonite impressions embedded in them.

It was all great fun, though now my knees are a little sore!

Posted by Kevin, F.C.D. at 10:06 PM | Permalink | Comments (1)

The past couple of days here have been miserable. Snow on and off all day yesterday, the value of today's highest wind gust (41) exceeded the value of the day's high temperature (35). Though I would have rather been out chasing birds on these final 2 days of my "break in service", I spent them playing Junior Invertebrate Paleontologist, instead. Yesterday I gently cleaned everything up then, today, got them all identified. I thought I would share some of the incredible detail on a few of them, too.

This first example is a straight ammonite named Sciponoceras gracile; straight ammonites are members of a family known as Baculites. Extinct, Baculites ranged from 7 cm (2.75 in.) to 2 m (6.5 ft.) in length, but the fossils are extremely fragile and rarely found intact. This fragment is 2.5 cm (1 in.) long, 1 cm. (0.4 in.) in diameter and is interesting because of the markings. The lines that you see are called sutures and divided the shell into chambers. Similar in some respects to the ballast tanks on submarines (I'm no expert by any means, but it is an easy way for me to explain this - even if not the correct scientific description), these animals could add/remove water from the chambers and thereby control their depth in the water column. Like all the other ammonites, Sciponoceras disappears from the fossil record 65 million years ago.

Perissoptera prolabiata, while extinct, is a member of a gastropod (snails and slugs) superfamily that includes modern conchs. Missing from this fossil is a "wing-like" extension that protrudes from one side. The attraction, of course, is the incredible detail that remains in the fossilized shell. Of the 3 I collected, this one exhibits much more of the shell detail and 1 still has the wing-like appendage (though little of the shell texture remains). Length is about 2.5 cm. (1 in.) and diameter (at the widest point) is 1.3 cm. (0.51 in.).

Another gastropod, Turritella whitei, was first described in 1893 by T.W. Stanton from the Tropic Shale. The fine detail in the coils around the shell are what makes this such a cool find (my last entry featured another one). Turritella species first appear in the fossil record in the Cretaceous and there are modern examples living today. This fossil is 3.5 cm. (1.375 in.) long.

Last we'll take a close look at a Pycnodonte newberryi. As noted in the last entry, these were all over the place at many of the limestone concretions. This one, at 2.5 x 2.0 cm. (1.0 x 0.79 in.), is not the largest I collected, but does feature a hole not found in the others. About 90 million years ago this oyster became a meal for a Gastropod that bored the hole then ate the tissue inside (then kindly left it for me to collect!).

Posted by Kevin, F.C.D. at 08:07 PM | Permalink | Comments (0)

fossiliferous adj. bearing or containing fossils; "fossiliferous strata"

I can think of no better way to describe the area I got to explore today with the director of the Bryce Canyon Natural History Association (the park's bookstore). Though we were outside of the park on private land, the Tropic Shale is one of the oldest sedimentary layers exposed within Bryce, and it is home to lots of fossils. The Tropic Shale are marine sediments that represent the period when the Western Interior Seaway (also called the Mid-Cretaceous Seaway) was at its greatest extent during the Cretaceous Period.

Mostly a dark gray dirt, I learned that you look around for "concretions" of limestone exposed as the dirt is carried down the hillside - this is where you look for fossils. These first 2 images are ammonites: cephalopods related to modern squids and octopi. The first is one with a coiled outer shell, the second with a slightly curved shell. Sometimes you find them just lying on the ground, sometimes they are embedded in the rocks. In the case of this second ammonite, I first found a rock containing the fossil's impression, then found the fossil itself after several minutes looking around in the rubble. An interesting fact about ammonites is that they are never found above the K-T Boundary: they became extinct at the same time as the dinosaurs 65 million years ago. The first measures about 5.25 cm (2 in.), the second 3.75 cm (1.5 in.).

Unfortunately I don't remember any of the exact names of the fossils I collected today (I have over 20 pounds of rocks and individual fossils), I'll be be getting all of that once I've had a chance to clean and sort. This is some kind of shellfish a Turritella species, a gastropod family that arose in the Cretaceous and still around today, measuring 3.2 cm (1.3 in.), very well preserved and still attached to the rock on one side. The rock that underlies the Tropic Shale is called the Dakota Formation and, across the highway from where we were working, radiometric dating determined the Dakota to be 93 million years old, making these fossils younger than that, but older than 65 million years. To me that is just amazing!

This is a small collection of some other examples; the three at the top are Pycnodonte sp., a type of extinct oyster. The first (left to right) is the outside top portion of the shell, the middle shows the inside of another shell, the one on the the right is the bottom part of a shell. The Pycnodonte are just everywhere - in one spot where I was standing there were thousands just lying there on the ground. These measure roughly 2.75 cm. (1.5 in.) On the bottom row we have another ammonite (4.25 cm., 1.75 in), a small clam (also 2.75 cm., 1.5 in.) and a gastropod - in this case a small marine snail type creature (2.5 cm., 1 in.).

All in all, it was a very interesting day (in the next few days I'll try to get the names and, when I do, I'll update the post).

Posted by Kevin, F.C.D. at 09:26 PM | Permalink | Comments (0)