Moveable Fossil Feasts

There are sites I consider moveable fossil feasts.  This is not in a Christian liturgical sense where the timing of a religious observation shifts from year to year.  Though a moveable fossil feast may, on occasion, exhibit some temporal impermanence, these feasts are much more about changing the locations of fossils.  Nothing divine about them, but, as a result of taking fossils from one site to another, likely more accessible, site, moveable fossil feasts offer collectors wonderful opportunities.

This terminology is mine alone.  I’ve never heard anyone refer to these sites in this fashion.  To be clear, I do not apply this term to places like the shoreline of the western Chesapeake Bay where fossils move as they erode from the Calvert Cliffs.  That process is natural.  In contrast, moveable fossil feast are human-made.  And, as such, the rewards they offer to fossil collectors are usually, but not always, a happy byproduct of the relocation of fossil-bearing sediment undertaken for some other purpose, such a beach replenishment.

This post offers brief descriptions of a few of the moveable fossil feasts with which I have some personal connection, either directly or indirectly, and one that I do not.  At the conclusion, I briefly highlight these sites' singular virtue and the challenging issues they raise.

North Myrtle Beach, South Carolina - A friend, sadly recently deceased, spent several weeks in different years vacationing with his wife at North Myrtle Beach, South Carolina.  They walked the beach a couple of times a day, outings timed with low tide.  As they went, they collected fossils – teeth, bones, shells – objects the waves had exposed on the beach.  A small sample from one year is pictured below.

These finds were often a stratigraphic and chronologic hodgepodge, a nightmare for identification.  Some came from the Pleistocene and Pliocene epochs (between 5 million to 11 thousand years ago), more from the Miocene period (23 to 5 million years ago) or the Cretaceous (143 to 66 million years ago).  Among the finds over the years were pieces of fossil turtle shells, ancient horse teeth, shark teeth, pieces of fossil sand dollars, and ammonite fragments.

My friend surmised this mixture resulted from efforts to replenish the beach, presumably with material dredged from offshore sedimentary layers from different time periods.  A competing or, perhaps, complementary explanation is that erosion of offshore sedimentary layers is the agent responsible for the fossils and their diversity.

C&D Canal (Reedy Point, Delaware) – I collected here twice many years ago.  It is a site created by the dumping of material dredged by Army Corps of Engineers in 1980 as it deepened the Chesapeake and Delaware (C&D) Canal.  The fossil-rich material hauled to, and deposited at, this site came from the Mt. Laurel Formation, dating from the Late Cretaceous. 

Here is a view of the location on one visit more than 15 years ago.

What was practiced here was mostly surface collecting, practitioners wandering through the overgrown and exposed landscape, eyes focused on the ground.  It was actually very easy hunting, though it took some time before the objectives of the searching came into view.  Most abundant (and obvious) were the orangey, long, pointed belemnites, the calcitic skeletal remains from the tails of the Cretaceous squid, Belemnitella americana.  Oyster shells (Exogyra) were also common.  Pictured below are some of these fossils.  An amateur’s rather old guide to the fossils from the Canal is suggestive of what could be found.

Is this site still there, still accessible?  I don’t know.  One source stated some four years ago, that the Army Corps of Engineers was planning to do more dredging and pile the dredged material on this site.  Unfortunately, this “new” material was slated to come from a formation lacking fossils.  Another source simply says it’s closed.  Such is the fate of, at least, this moveable fossil feast.  

Aurora Fossil Museum, Aurora, North Carolina – Located near the Lee Creek Mine, a phosphate surface mine that, when it was open to collectors, yielded stunningly beautiful fossils, particularly those from the megashark Otodus megalodon.  The various Lee Creek fossils come mostly came from the Pungo River (Lower Miocene) and the Yorktown (Early Pliocene) formations.  Not unexpectedly, the areas where we could collect, when we permitted into the open pit mine, were not pristine, not as they were originally laid down, but, rather, we needed to figure out which formations might have contributed to the areas in which we were collecting.  For me, at least, that was not always clear.

Now, I don’t consider the mine itself to have been a moveable fossil feast because collectors went to where the fossils originated, albeit in strata that were highly disturbed by the mining process.

No, the moveable fossil feasts, for me, are the spoil piles of material hauled from the mine and deposited outside the Aurora Fossil Museum in Aurora, North Carolina.  Purportedly, this material consists of tailings from the Pungo River formation which, even if true, does not locate these fossils within the various units that make up this formation. 

When I was last there – some 15 years ago – this was the view toward the spoil pile where I hunted a couple of times, once when a trip to the mine was cancelled at the very last minute and once after a successful hunt at the mine.

The museum has evolved greatly since then and, among other changes, now has two pits of material from the mine.

The finds were small, though relatively abundant; searching on one’s knees was rewarded.  Here is a sampling of what turned up on one of my hunts through the spoil piles.

This moveable fossil feast is wonderfully accessible, located in a small town with parking just a short stroll away.  It’s all rather domestic as attested to by the cat who oversaw my activities.  (The cat may have had other intentions for the sand of the fossil pit.)

Bradenton Beach, Florida – The same friend who enjoyed the moveable fossil feast at North Myrtle Beach was vacationing one year at Bradenton Beach when he came upon this scene in a parking lot serving the beach.

Never inclined to ignore the possibility that fossils might be had, he explored these huge mounds of gray, phosphatic sand and discovered a true wealth of shells, most in fantastic condition.  He spent much of his vacation climbing up and down this sandy landscape, gathering shells.

These were, indeed, fossil shells because he learned that the sand had been hauled to this location from an area quarry which he concluded was the SMR Mine in Sarasota, making these fossils Pliocene, about 3.6 to 3.0 million years old.  Here are three beautiful specimens I obtained from him.

Though this moveable fossil feast was extremely accessible (in a parking lot, of all places), my friend searched these sandy hills quite feverishly because all of this material was slated shortly to be crushed to pave the parking lot.

Rotterdam Harbor, The Netherlands – This last moveable fossil feast, international in nature, was featured in Nina Siegal’s article titled On the Hunt for Mammoths which appeared on November 17, 2025 in the online version of The New York Times (print edition ran the article on November 19, 2025).  

This feast has features reflected in some of the descriptions I’ve already provided of such sites, but there is a remarkable attribute that sets this one apart, prompting me to think – “The Dutch know how to do this.”

In the article, Siegal describes how people are hunting for fossils along at the Maasvlakte 2 beach, on the harbor shoreline in Rotterdam, benefitting from a beach reclamation project – no, more like a beach construction project.  This beach is wholly constructed of sediment dredged from the sea floor of the North Sea, sediment roughly 2.5 million to 11,700 years old.  This sediment comes from what once was a steppe where megafauna animals lived.  As a result, the material used to build the beach contains the fossil remains of many land animals, such as woolly mammoths, woolly rhinos, and giant horses.  Sprinkled among these are fossils from invertebrates including sharks.

Now, here’s where it gets truly amazing.  What sets this moveable fossil feast apart from the others I’ve described so far is the incredibly well organized scientific support for the amateur fossil collectors who scour the beach.  In The Netherlands, these fossil hunters are permitted to keep their finds, but they are also encouraged to register them with the online Oervondschecker (“Primal Find Checker”), initiated by the Port of Rotterdam Authority and now maintained by the Naturalis Biodiversity Center.  (The default language on the site is Dutch, so having a browser translate the text is useful for some of us.)  As the website states:  “Every notification will be reviewed within a few days by an expert.  A find gets a provisional determination and an (estimated) time determination.”  Marvelous.

How does Naturalis do that?  Each collector seeking to register a find is asked to submit pictures of it with the precise GPS location of where it was found (ah, the wonders of the smart phone) or, at a minimum, they are advised to use the app to locate the find on its associated map of the beach.  As the Naturalis Biodiversity Center explains on the website, the dredging operations were “accurately tracked,” including the depths at which the sand was “sucked up” during each trip.  Data on the geologic origins of the individual layers of sand at the seabed in the North Sea feed into the Naturalis calculations.  Further, where the dredged sand was deposited on the beach was also meticulously followed.  As a result, the general provenience of a find can be determined and used to estimate its age.  That is truly amazing.

In conclusion, my descriptions of these few moveable fossil feasts suggest a cardinal virtue as well as a couple of sins associated with them.  The single most important positive attribute of these sites is that, as a result of human intervention, fossil-rich sediment has been moved from one location to another, a place that is typically much more accessible and convenient for collecting.  Fossil hunting at them can be easy – e.g., going through the Aurora Fossil Museum fossil pits or walking the beach at the Rotterdam Harbor.

On the other side of the ledger, these sites have certain downsides.  Having separated sediment from their original location, the makers of these sites (with the important exception of the Rotterdam Harbor beach) sever the ties between the fossils and the geological strata where they were originally found.  Identification and age determination can be difficult, and sometimes, though not always, impossible – the finds on North Myrtle Beach, for example, are a challenge.  Another key negative attribute is that they can be transient, sometimes offering only a limited opening for collecting - the material in the Bradenton Beach parking lot is a striking case in point.

Still, they are a wonderful phenomenon and taking advantage of them, no matter the challenges, is a delight.

A Baseball Roster: The-All Geology and Paleontology Team

This post has little to do with natural history.

Bluebirds have returned and are scoping out bird boxes.  Buds are brushing color onto trees.  Some days are actually warm.  Memories of a brutally cold winter have faded.  Clearly, it's time for baseball.  For this post, I was largely inspired by my recent discovery of an intimate and quirky publication imbued with all things baseball, the Elysian Fields Quarterly (EFQ).

The EFQ began life in 1981 as The Minneapolis Review of Baseball:  A Journal of Writing on Baseball (MRB), segued into the EFQ, and died in 2008.  For its owners and editors, it was (mostly?) a labor of love (apparently making money didn’t factor into it).  They worked to produce a journal that would be, according to Ken LaZebnik, who conceived of MRB:

a quasi-literary quarterly that would provide a forum for baseball fans everywhere, from any walk of life, to express their interest in and abiding affection for the National Pastime.

Macalester College holds a nearly complete run of both publications and a vast array of other associated material.  The LaZebnik quotation above is taken from the historical note in the Macalester College Archives guide to the Elysian Fields Quarterly/ Minneapolis Review of Baseball collection.  This quotation was originally posted on the EFQ website, a site which is no more. 

I am more familiar with the EFQ, though I think much of what I have to say about it also applies to MRB.  The EFQ embraced baseball, but, more importantly, it was devoted to publishing writing about baseball in all, or nearly all, possible forms:  history, fiction, essays, poetry, puzzles, interviews, book reviews, quizzes, statistical analyses, and so on.  Among the EFQ regular offerings was a column titled Rosters.  It's this last "literary" form that is the focus of this post.  (I would note that baseball-related photography and art were also part of the journal's reach.)

The Rosters column was a clever and playful deep dive into the names of major league baseball players.  The objective for this feature was finding enough players with names (mostly last names) that reflect some chosen theme and whose playing positions cover all of the positions needed to field a team.  For instance, the Fall 1994 EFQ issue included a roster compiled by Steven Lichtman of players whose names were appropriate for The All-Home and Hearth Team and whose positions filled out a roster.  His roster had, among other players, Alan Bannister at shortstop and Tommy John among the pitchers.  In addition to the roster by Lichtman, my copies of EFQ include rosters fashioned by Mikhail Horowitz.  The editors wrote the first Roster - The All-Fish Team - which appeared in the last issue of MRB.  It was accompanied by a call for rosters to be contributed by readers.

Inspired by their efforts, I have tried my hand at creating a roster for The-All Geology and Paleontology Team.  (None of the roster columns in my very small sample of EFQ issues or in any of the issues listed on eBay that I've looked at covers this same theme.)  The roster I filled out is very heavy on the geology side, barely touching paleontology.  To populate my roster, I first went through my print copy of The ESPN Baseball Encyclopedia, Fourth Edition, 2007, then, to fill a gap or two in the roster, I went to the online Baseball Reference, a great source of baseball statistics and history.  I used the Baseball Reference to create the player profiles given below.  Of note, I limited myself to players who took the field before 1940.  I also did not expand my roster to add additional "bench" players or add a manager.

I found this to be a sobering, even melancholic, enterprise.  For many of these players, their major league careers were starkly brief moments, their presence barely recorded in the game’s annals.  I suspect that, for at least some, the experience carried an outsized weight.  Thoughts and, perhaps, regret about what might have been?  Though I did not deliberately seek out obscure players, no one on my roster is a household name.

In my annotated roster below, I first list the position, the player filling it, and his birth and death years.  Below that, I record the player’s full name, describe the length of their career and which teams they played for, and conclude with mention of an item or two that struck me as, at least, somewhat memorable about their career.  The EFQ rosters were not annotated.  (A glossary explaining most of the baseball terms and statistics cited in my annotations can found on the Major LeagueBaseball website.)

Here, then, is my all-geology and paleontology team roster:

First Base: Les Rock (1912-1991)

Lester Henry Rock played in two games for the Chicago White Sox in 1936.  He came to bat just once in his career, entering his first game as a pinch hitter.  He grounded into a double play and a runner scored on the play.  Under the rules in place at the time, Rock was credited with a run batted in (RBI).  Only a few years later, a rule change would have deprived him of that RBI.

Second Base: Charlie Pick (1888-1954)

Charles Thomas Pick played in the major leagues from 1914 through 1920, for the Washington Nationals, Philadelphia Athletics, Chicago Cubs, and Boston Braves.  In his debut in the majors, he had three hits in his first three at-bats.  He holds the major league record for most times at bat in a game without a hit, 11.

 

Shortstop: George Bone (1874-1918)

George Drummond Bone played for the Milwaukee Brewers in 1901.  He appeared in 12 games with a batting average of .302.  Baseball Reference gets into the roster game when it notes that "he is a cinch to make the 'All Body Part' team, along with players such as Dave Brain, Roy Face, and Harry Cheek."

 

Third Base: John Karst (1893-1976)

John Gottlieb Karst appeared in a single game for the Brooklyn Dodgers in 1915.  He was a fielding substitution for the starting third baseman and helped turn a double play.  He never came to bat.

 

A karst is a limestone landscape where water has created sinkholes, caverns, underground streams, among other features. ( John O.E. Clark and Stella Stiegeler, The Facts on File Dictionary of Earth Science, 2000.)

 

Catcher:  Silver Flint (1855-1892)

Frank Sylvester Flint played in 1875 with the St. Louis Red Stockings, then spent a couple of years in the minor leagues, before returning to the major leagues in 1878 with the Indianapolis Blues.  From 1879 through 1889, he played for the Chicago White Stockings.  He briefly managed the White Stockings in 1879 while also playing.  During his career, he was the catcher for three no-hitters.  (A "no-hitter" - a term not defined in the MLB glossary - is a game in which one side fails to make a hit during the entire contest.)

 

Outfielder: Bill Clay (1874-1917)

Frederick C. Clay appeared in three games in 1902 for the Philadelphia Phillies, batting eight times with two hits and a run batted in.  In his debut, he had two hits in four at-bats.

 

Outfielder:  Jerry D’Arcy (1885-1924)

Jeremiah Joseph D’Arcy played for the Pittsburgh Pirates in 1911.  He had six at-bats over the course of two games, but failed to make a hit.  According to Baseball Reference, D’Arcy was “a player whose true identity long eluded researchers.”  A "Jerry Dorsey" reportedly played for the Pittsburgh Pirates for two games in 1911, but much of information on the man was contradictory or missing.  It wasn’t until 2013 that it was proven that Dorsey was, in fact, a person named Jerry D’Arcy.

 

In geology, a darcy is a unit of measure of the permeability of rock.  (John O.E. Clark and Stella Stiegeler, The Facts on File Dictionary of Earth Science, 2000.)

 

Outfielder:  George Stone (1876-1945)

George Robert Stone played in 1903 for the Boston Americans, and then from 1905 to 1910 with the St. Louis Browns.  Stone was a good hitter with a career batting average of .301.  In 1905, he led the American League in hits (187) and topped the major leagues in batting average in 1906 (.358).

 

Pitcher:  Shovel Hodge (1893-1967)

Clarence Clemet Hodge appeared in 75 games for the Chicago White Sox from 1920 through 1922.  Of the 20 games he started, he pitched complete games in 8.  Baseball Reference reports that he was called “Shovel” because, at one time, he was quite heavy and brought to mind a steam shovel.

 

Pitcher:  Bob Spade (1877-1924)

Robert Spade debuted in 1907 with the Cincinnati Reds at the age of 30 and played for them until 1910, when he was traded mid-season to the St. Louis Browns.  His career ended after 1910.  His most impressive season was 1908 when he had a record of 17 wins and 12 defeats.  That season, he started 28 games and pitched complete games in 22 of them.

 

Pitcher:  Reese Diggs (1915-1978)

Reese Wilson Diggs pitched for the Washington Nationals in 1934, appearing in four games.  That year, he was the youngest player in the American League.  He started three games and pitched complete games in two.

 

Pitcher:  Ray Miner (1897-1963)

Raymond Theodore Miner pitched one inning in one game for the Philadelphia Athletics in 1921.  It was not a good outing because he gave up two hits, walked three batters, and yielded four runs.  He has a statistically weird claim to fame, starting his career, ending it, and dying on the same month and day:  September 15.  Strangely enough, he’s not the only major league player to have achieved this distinction.  Lou Raymond made those three transitions on May 2.

Since I was attempting to emulate them, I thought it might be interesting to learn a bit about the two authors who composed rosters in the issues I own of the EFQ (one column by Lichtman and several by Horowitz).  When Steven Lichtman’s roster column appeared in the Fall 1994 issue, he was a newly minted lawyer.  He later earned a PhD in political science and is now an associate professor at Shippensburg State University.  Though he doesn’t list the EFQ roster column in his curriculum vitae (understandable in the scheme of things), I don’t think he abandoned baseball completely.  At one point in his wandering in the academic wilderness of two-year appointments, he taught at Dickinson College.  An article about his impending departure from the college appeared in the May 20, 2005, issue of the Dickinson student newspaper.  It quoted a student who said of Lichtman:  “He was equally willing to discuss John Stuart Mill's 'On Liberty' as that night's baseball game."  

Mikhail Horowitz was described in the EFQ as “the author of Big League Poets (City Lights, 1978) and a contributor to many outré baseball anthologies.”  That doesn’t quite capture his multifaceted career as a poet, musician, writer, journalist, comedian, and satirist; baseball runs through his poetry and creative output.  A recent interview offers some insight.  (Howard Altarescu, Writers of the Catskills:  In Conversation With Mikhail Horowitz, TheOverlook, December 25, 2025.)

I think I’m in good company.

The Contradiction of Robins

In woods in mid-winter, living trees, shorn of leaves, join their dead companions in extending naked branches to the sky.  What was hidden in summer behind a green curtain is revealed.  The track along the edge of the pond near my home takes me to a point where, across the frozen surface, I now can see through the trees to where I started.  As a result, though the horizon has expanded in this season, this pond today seems much smaller.

In the mid-Atlantic region of the United States, this February has been bitterly cold and battleship gray with little hint that we are heading to spring.  Yet, the days are inexorably growing longer.  A full hour of sunlight will be gained between now and mid-March, though it won't feel that way amid the rain, the snow, the gray.

One of the contradictory phenomenon of winter throughout much of the central and eastern U.S., particularly at lower latitudes, is the bird we salute as the herald of spring, the American robin (Turdus migratotius).  Although it is actually with us through much, if not all, of this bleak season.  On my winter walks, robins have been my frequent companions, sometimes signaling their presence just by calling, and, sometimes, by swooping in large numbers onto the trees and bushes that still bear fruit (or, at least did, until the marauding robins descend).

I recently read Margaret Renkl's inspiring and graceful The Comfort of Crows:  A Backyard Year (2023).  Its essays track the passage of a year in the events and changes in the natural world, largely in Renkl's Nashville backyard.  The life and death, losses and gains, the comings and goings in that world move and educate her as she deals with changes in her own life, and responds to the chaos that has overtaken the country.  Ultimately, the persistence and resilience of the natural world offers her hope.  In nature, she remarks, "so much life springs from all this death that to spend time in the woods is also to contemplate immortality."  (p. 259)

What prompted me to write this post is a passage early in the book.  In a chapter set in winter, she cites a tradition among birders that the first bird seen in a new year will characterize the kind of year you will have.  One year, she spots a passing woodpecker but cannot determine if it is a downy or a hairy, so she goes with the second bird sighted, a robin.

I love robins. . . .  I love the way they flock up in winter, with the locals and their new offspring welcoming the migrators to a season-long family reunion.  (p. 5-6)

Renkl's portrayal of the local robins sharing their winter home with those migrating through pleased me, prompting research on the bird's migration patterns, including the relative balance between robin homebodies and travelers, and how far the latter actually migrate.

I admit that I've always found the robin's scientific genus name a bit off putting, in part because it evokes South Park.  But the Latin root for Turdus means "thrush" which the robin is, being a member of the thrush family Turdidae.  It's the species name that I think revealing because its dual meanings capture the bird's contradiction I just cited.  The Latin root of migratorius means both "migratory" and  "wandering."  Robins are restless creatures, they all wander, even those who seldom travel far from home.  Their search is constant for a supply of soft-bodied invertebrates in some months and fruit in others.

Populations of robins may be comprised of both migrants and year-round residents.  Indeed, this is possibly true of the majority of bird species.  For robins, this phenomenon has been explored by biologists David Brown and Gail Miller, using data on bird banding and recovery from 80 years of Federally supported bird banding.  They looked at robins in these data for which there were observations in both the breeding season (May to August) and the wintering season (November to February).  They defined individual, local/non-migrant robins as those for which the distance between locations of observations in breeding and wintering months was less than 100 km; all others were considered migrants.  (Band Recoveries Reveal Alternative Migration Strategies in American Robins, Animal Migration, Volume 3, 2016.)

Their findings document the overall complexity of the migratory behavior of T. migratorius.  Overall, they find 80 percent of recoveries to be migrants.  The distance traveled by migrants is stunning.  Of migrants, some 96 percent (nearly 77 percent of all robins) traveled 500 to 2,100 km from their breeding sites.  Curiously, the further south a migrant robin wintered, the further it had migrated.

A fifth or 20 percent of robins covered by their data stayed locally across breeding and wintering seasons, a phenomenon that has been increasing since 1980.  Overall, non-migrants moved on average slightly less than 21 km between these seasons.

A more detailed study of the movements of a small number of robins over a year suggests just how complicated migration can be for these birds, and how generalizations may fail to capture the reality.  Alex E. Jahn, et al. tagged 31 robins in the 2017 breeding season with devices that recorded their movements.  (First Tracking of Individual American Robins (Turdus migratorius) Across Seasons, The Wilson Journal of Ornithology, Volume 131, Number 2, 2019.)  Although only 7 of the birds were recaptured in the 2018 breeding season, the journeys of these birds over the course of the year were fascinating, almost idiosyncratic.

Of the 11 tagged in Alaska, 4 were recaptured.  By the middle of September, these robins had left Alaska, flying into western Canada.  A month later, some had reached Montana and North Dakota.  One ultimately reached Texas, 4,480 km from where it originated; another migrated 4,508 km to Oklahoma.  Only one of the 14 birds tagged in Massachusetts was recaptured a year later.  That bird first lingered during the fall near its breeding grounds, only leaving Massachusetts in November.  Then, over the course of 20 days in early November, it winged its way to South Carolina, a distance of 1,210 km, where it overwintered.  Finally, of the five robins tagged in the District of Columbia, only two were recaptured and both stuck around their home territory for the entire year, migrating not at all.

The routes migrating robins follow during any particular journey south may not be fixed, possibly varying from year to year (bird to bird?).  The Cornell Lab's entry for the American Robin in Birds of the World, posits:

The term 'routes' does not really apply to robin migrations and there does not appear to be strong connectivity between overwintering and breeding grounds.  Indeed, evidence from banding records shows that robins in a particular area originate from widely scattered areas to the north.  (E. Natasha Vanderhoff, et al., American Robin, Birds of the World, Cornell Lab of Ornithology, 2020.)

Indeed, migrant status from year to year may not be immutable for individual robins.  Though Brown and Miller concede that their data do not allow them to determine whether any specific bird migrated one year but not the next, they add:  "It is possible, especially given the typically vagrant nature of robins during the non-breeding season."  (p. 43)  I am really taken with the idea that the impulse to migrate at all might be up for grabs for individual birds from year to year.

Ultimately, I believe that the robin's migratory behavior, bridging the seasons, offers some solace in this world where life inevitably leads to death.  Robins are heralds of restorative spring, the season when life is new and renewed, and, in the dark days of winter, they show that, even then, life persists.

Sea Urchin as Canvas

The fossil pictured below is an echinoid (sea urchin) some 84 to 90 million years old from the middle of the Upper Cretaceous period.  This post explores how this particular specimen, as well as most of the other members of its specific taxon, served as a "canvas" that was intricately "decorated" postmortem.  It concludes with a very plausible explanation of why.

The first photo shows the apical (apex) side of the fossil (the side where, in life, waste products were expelled); the second is of the oral side.

Echinoids originate in the fossil record in the Middle Ordovician period (471.3 to 458.2 million years ago) and are with us still.  They come in a variety of spherical, usually globular, shapes.  A calcium carbonate skeleton or test made up of interlocking plates encloses the internal organs of the animal.  In life, the test is covered with spines giving the animal the name "urchin" which, in Middle English, means "hedgehog."  (Sea Urchins:  Strange and Spiny Wonders of the Ocean, Holly Chetan-Welsh, Natural History Museum, London.)  The spines are typically lost when the animal dies.

In my well worn (and surely dated) copy of Invertebrate Fossils (1952), geologist Alfred G. Fischer notes that the echinoids are divided into two groups:  Regularia and Irregularia.  The former have a clear and distinctive pentagonal symmetry; the latter show a bilateral symmetry.  The two groups differ as to their life style.  Regular urchins live on the surface of the sea bottom.  Fischer quaintly says of the regular urchins:  "some wander about on their spines, as on stilts, while others clamber over submarine cliffs by means of their prehensile tube feet, or nestle in rock cavities."  (p. 705)  In contrast, the irregular urchins are adapted to soft, muddy sea floor sediments, often burrowing into the substrate.

The echinoid pictured above has the distinctive overall heart shape that marks it as an irregular urchin of the spatangoida order.  The distinguishing heart shape evolved, according to Fischer, to facilitate the animal's deep burrowing into the sea floor.

The apical side of this specimen displays a set of radiating plates, all but one in a quite distinctive petal shape.  That outlier, the one pointing to the top of the picture and leading to the indentation of the test, appears slightly less well defined.  This specimen is of the genus Micraster, and I accept the original collector's identification of it as a M. coranguinum.

This specimen was collected in Spain from a portion of the Olazagutía Formation that spans the Coniacian (89.9 to 85.7 mya) and Santonian (85.7 to 83.6 mya) ages of the Cretaceous period.  These fossils are very abundant in this formation which is composed of sedimentary layers of marl and marly limestones.  In general, marls are a blend of carbonate (usually calcite) and siliciclastic (silt and clay) muds:  the marl tends to marly mudstone as the siliciclastic proportion increases and to marly limestone as the carbonate proportion increases.  (Samuele Papeschi's "Marl" entry on his Geology is the Way website is an excellent introduction to marls.)  The ocean floor in the Olazagutía area during the Upper Cretaceous was soft and muddy, ideal for a burrowing irregular echinoid like Micraster.

I noted at the opening of this post that this echinoid and others of its ilk were thought to have been decorated after death (more on that timing below).  The "artists" in question were so-called sclerozoans.  These are animals that, in this instance, attached themselves to the surface of the test after the urchin died, some to drill into or otherwise penetrate the urchin plates, presumably in search of whatever remained of the dead urchin, and some to secure a solid perch.

The term sclerozoan was proposed in 2002 by paleontologists Paul D. Taylor and Mark A. Wilson to describe an animal "fouling any kind of hard substrate."  (A New Terminology for Marine Organisms Inhabiting Hard Substrates, PALAIOS, Volume 17, Number 5, October 2002.)  I like the term "fouling" applied to what these animals and their plant counterparts (sclerophytes) do to these surfaces.

In the images below, I have focused on several of the "ornamentations" left by the sclerozoans on this particular Micraster specimen.  In general, I can only suggest the broad taxa from to which these animals belong.

The first shows a close up of the worm tube on the oral side of the test.  This could be the work of worms in the Serpulidae or Spirorbidae families.

This next picture is the signature of a bivalve that encrusted the test on the edge of apical side of the test.  The species responsible could be Atreta sp.  I do not know what the little oblong object is that appears above and to the right of the shell, but it would appear that it dug into the urchin test.

This last picture is of ichnofossils, that is, the traces left by the action of some living organism.  What entity is responsible for an ichnofossil is not often known with any certainty.  In this case, the little cuts into the urchin test were left by some boring animal; these markings are identified by paleontologists as the ichnogenus Rogerella.  If evidence from extant animals is any guide, the actor in question was probably a barnacle of some sort.

These are only a very few of the traces of sclerozoan activity on this test.  A fascinating study of Micraster echinoids from the Olazagutía Formation by researcher Samuel Zamora and his colleagues lays out the wide range of signs of sclerozoan activity upon and in Micraster tests from this formation.  In their paper titled The Infaunal Echinoid Micraster:  Taphonomic Pathways Indicated by Sclerozoan Trace and Body Fossils From the Upper Cretaceous of Northern Spain (Geobios, first available online January 11, 2008), Zamora et al. present the results of analysis of 100 Micraster specimens collected from the Cementos Portland quarry near the village of Olazagutía, Spain.  These fossils were found in a layer dating from the Lower Santonian age.

I would note that it is a section of the Olazagutía Formation exposed in this particular quarry which has been accepted as defining the base of the Santonian age.  The bivalve Platyceramus undulatoplicatus first occurs there.  (M.A. Lamolda, et al., The Global Boundary Stratogype and Section Point (GSSP) for the Base of the Santonian Stage, "Cantera de Margas", Olazagutia, Northern Spain, Episodes, Volume 37, Number 1, March, 2014.)

What I found remarkable about the study by Zamora and colleagues was that 95 (95 percent) of the 100 Micraster echinoids they analyzed showed evidence of activity by sclerozoans, either living on the test surface (94) or digging into the test (71).  Though my specimen shown above may not be from precisely the same location as those considered in the study, it certainly reflects the same evidence of sclerozoan activity as those analyzed by Zamora et al.

This raises the question:

Why did these urchin tests prove so irresistible to sclerozoans - those encrusting or drilling animals - in this general time and place?

 Zamora and colleagues proffer an answer I find elegant and convincing.  First, as I noted earlier, this activity on and in the urchin tests likely occurred after the death of the echinoids.  Zamora et al. posit this timing is true because, while alive, these urchins lived burrowed into the muddy ocean floor and were protected by spines.  Both of these attributes ward off sclerozoans.  Second, after death, the echinoids' tests lost their spines and the tests were likely to have been unburied at some point.  Third, in a key assertion, the authors write:

In the argillaceous-carbonate, muddy bottoms of the Upper Cretaceous marine platform of the Olazagutía area, exhumed endobenthic echinoids tests constituted small, yet stable island environments on which several biological groups found a place for settling (94% of the tests found are colonised).  (p. 23)

"Small, yet stable island environments . . . ."  Lovely image.  Given the abundance of Micraster echinoids, their tests constituted many, many such small islands.