Which came first?

May 27th, 2010

NEW ALBANY, MISSISSIPPI — The Cretaceous oyster above was collected from the Coon Creek Beds of the Ripley Formation (Upper Cretaceous) near Blue Springs, Mississippi.  The holes are borings called Entobia which were produced by clionaid sponges which built a network of connected chambers inside the shell so that they could carry out their filter-feeding with some safety from grazing predators.  The branching white fossil is a cyclostome bryozoan, probably Voigtopora thurni.  Which was present first on the shell, the borings or the bryozoan?  Is there evidence that they were living at the same time?  The largest holes are about two millimeters in diameter.

Fixing your search images

May 26th, 2010

NEW ALBANY, MISSISSIPPI — The kind of science our paleontological field team is doing ultimately depends on unpredictable discoveries.  We came to this part of the world based on the recorded experiences of generations of geologists who assembled maps of rock types, calculated stratigraphic ages, and made long lists of fossils they found.  From this body of knowledge we could estimate our chances of finding certain kinds of fossils in certain places.  Nevertheless, as with those pioneering scientists, we ultimately have to find things on our own.

Scouring the ground for fossils in the Nixon Sand Facies of the Prairie Bluff Formation (Upper Cretaceous) in Pontotoc County, Mississippi.

The old adage that “you find what you’re looking for” has some truth in exploratory paleontology.  You have to know what your target fossils look like before you can collect them.  This means recognizing them despite their orientations in the sediment or their preservation.  We develop a “search image” over time for each particular types of fossil.  Paul Taylor, for example, can pull bryozoans off the ground right under my nose because he has trained a set of search images for decades.  On this trip we have all learned what to expect when we crawl across the Prairie Bluff or Clayton formations.  It is an honor to spend a day plucking little treasures from the ground and adding them to the store of human knowledge.

A Cretaceous oyster encrusted in the top left of the shell with a bryozoan and drilled by a predatory snail in the center, with a coin showing The Great Emancipator for scale (Troy Beds, Ripley Formation, Pontotoc County).

Geologists a bit weathered after a week of southern sun

May 26th, 2010

A week’s worth of fieldwork done.  All is going well.  We have learned so much since we arrived last week so fresh and clean.  Mark Wilson, Caroline Sogot, Megan Innis and Paul Taylor.  Two more days of fieldwork to go.  Bags and bags of fossils already collected.  Photo taken at Rockin’ G Ranch, Pontotoc County, Mississippi.

An abundance of Cretaceous shark teeth

May 25th, 2010

Shark teeth found in the Upper Cretaceous Prairie Bluff Formation in Starkville, Mississippi.

STARKVILLE, MISSISSIPPI — OK, Andrew Retzler, please identify these teeth as best as you can in the comments below!  For everyone else, Andrew will be leaving with me in little more than a week for Israel where he will be collecting Late Cretaceous shark’s teeth as part of his Independent Study project.  He already proved very adept at sorting out a set of Israeli fossil shark’s teeth I had collected last year, so we’re giving him some more practice before his fieldwork.  It is possible we will have collected enough teeth by the end of this trip that he will be able to use them for comparisons.  Megan has proven especially good at finding teeth and other shark bits.

We meet the Cretaceous-Tertiary boundary in Mississippi

May 25th, 2010

STARKVILLE, MISSISSIPPI — George Phillips took us to a series of Starkville outcrops today straddling the Cretaceous-Tertiary boundary.  The boundary here is gradational and generally marked by a color change from gray in the upper Prairie Bluff Formation to light brown in the lower Clayton Formation.  Since we want to collect fossils just below and just above the boundary, these localities were ideal for us.

Megan Innis and George Phillips at the Cretaceous-Tertiary boundary in Starkville, Mississippi.

We were able to collect many encrusters and borings above and below this fateful event horizon.  I was most impressed by the diversity of encrusting foraminiferans on shells and phosphatic pebbles on both sides of the K/T, apparently showing little effects of the extinction.  A long time ago I did some systematic and paleoecological work with this group, so I may return to them to test these observations.

We also noted the proliferation of tiny oysters (especially Pycnodonte pulaskiensis) in the Clayton sediments immediately above the extinction horizon.  These are part of the initial survival and recovery fauna and thus keys to the future repopulation of this shallow marine ecosystem.

Small oysters in the lowermost Clayton Formation (Paleocene) in Starkville, Mississippi.

New Member of the Cretaceous-Tertiary Southern USA Team

May 25th, 2010

STARKVILLE, MISSISSIPPI — We simply could not do this work without the guidance of local geologists who know the stratigraphy and the locations which are likely to yield the best results.  This is especially true in eastern Mississippi where most of the outcrops are in drainage ditches, cleared building lots, and on grass-covered roadsides.  There is no way we would find them on our own.

Fortunately we now have an extraordinarily knowledgeable colleague who has an ambitious schedule of fossiliferous localities to show us.  George E. Phillips met us as arranged at our first outcrop in Starkville this morning.  At first when I saw him get out of his official state vehicle in his impressive uniform and begin talking to Paul I thought we were about to be arrested.  Far from it, of course.  George is the Paleontology Curator at the Mississippi Museum of Natural Science and the Mississippi Department of Wildlife, Fisheries & Parks in Jackson.

Paul Taylor and George Phillips on the Avalon outcrop of the Prairie Bluff Formation (Upper Cretaceous) in Starkville, Mississippi.

George is a skilled paleontologist and general naturalist who knows just what sort of fossils we need for our work, and all the right places to find them.  We are very impressed that the state of Mississippi employs such scientific talent and makes it available to visitors like us.

Our first vertebrate fossil

May 24th, 2010

Megan found this beautiful shark's tooth in the Prairie Bluff Formation (Upper Cretaceous) near Starkville, Mississippi, this afternoon. Andrew Retzler! We want your expert identification of it in the comments below. Thanks!

From Alabama to Mississippi

May 24th, 2010

STARKVILLE, MISSISSIPPI — Early this morning we left Demopolis, Alabama, and drove to Livingston, home of the University of West Alabama.  Our first localities, in fact, were very close to campus as we again explored the Upper Cretaceous Prairie Bluff Formation.

Megan, Caroline and Paul doing the paleontology thing on an outcrop in Livingston, Alabama (N 32.59827°, W 88.19301°). The scene looks pretty quiet and usually is, except for the occasional utterance like, "Cool! More cyclostomes!". It is a culture all to itself.

In the early afternoon we crossed the border into Mississippi.  It may be our imagination and a limited sample size, but we swear the accents got thicker and the British among us especially had difficulty understanding it.  The fossils, though, know no boundaries and were just as good as their Alabama cousins.

A bored Cretaceous oyster waiting patiently to be picked up on a Mississippi outcrop of the Prairie Bluff Formation (N 33.48371°, W 88.85309°).  The fossils here are found on a dried mud so when you pick them up they give a satisfying sound as they detach from the ground.  It is like opening a sealed package knowing you're the first to find it.

A bored oyster waiting patiently to be collecting on a Mississippi outcrop of the Prairie Bluff Formation (N 33.48371°, W 88.85309°). The evenly-spaced holes were produced by an endolithic clionaid sponge. Note the splendid preservation of the shell and just the right kind of weathering. This is the kind of outcrop where you wonder why more people aren't here picking up this great stuff!

Her Majesty's Own Bryozoologist, Dr. Paul D Taylor, in action on a Mississippi outcrop. (Shout-out to Emma: This is the best I can do with your father. Always crouching close to the ground, he is. Bendiest man in paleontology.)

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