Tuesday, February 27, 2024

From the Chronicles of the Demise of My Fossil Collection: Revelations of Some Pufferfish Fossils

I began writing this blog in December, 2008, a year or two after I started seriously collecting fossils.  Over the years I wrote about a wide range of topics related to paleontology and natural history, but I focused frequently (though much less so recently) on my adventures in collecting.  This post signals that I am into a new phase in my fossil collecting:  its endgame.

As part of a general downsizing of home and possessions, I am dismantling the bulk of my fossil collection.  My sense of regret over the process is prompted not so much by the dispersal of the fossils, but rather by the choices I made over the years for the collection, particularly how I stored and identified what I collected.  In the course of breaking things down, I came upon three fossils collected over 15 years ago (just prior to beginning this blog and early in my collecting); what they say about my collection is the focus of this post.

Here is the first of those fossils, a spindle-shaped piece of fossilized bone.

It came out of a drawer in one of the many small organizer cabinets (designed originally for workbench items like nails and screws) that housed much of the collection.  Overall, these drawers held more than a thousand baggies, often with more than a single fossil inside.  This specific bag shares one specific feature with nearly all of the others:  a label that identifies location and date of collection.  Where it differs from most of the bags is that the specimen inside is clearly not a shark tooth.

I did much of my collecting in a very few locations:  the western shoreline of the Chesapeake Bay, Maryland (fossils date from a swath of the Miocene Epoch, say roughly 18 to 8 million years ago); the shoreline of the Potomac River at Purse State Park, Maryland (fossils here are from the late Paleocene Epoch, about 59 to 56 million years ago); and a creek bed at Science Drive, Maryland (the hard-won fossils here date from perhaps 74 to 66 million years ago in the late Cretaceous Period).

According to the label on the bag shown above, I collected the fossil at the Lee Creek Mine, North Carolina, which, when we could collect there, yielded beautiful fossils from the Miocene, Pliocene, and Pleistocene Epochs, from perhaps about 14 to 1.5 million years ago.  I entered the mine (not quite what it sounds like given that the mine is a working surface phosphate mine) on Sunday, October 12, 2008, a truly remarkable occasion because I had gained access to this place considered quite holy by fossil collectors.  A picture I took that day shows the scene with a scattering of collectors in pursuit of treasures.

From this landscape of hills of grey sand punctuated by wide pools of dark water could come an amazing array of fossils, none more sought after than the teeth from the shark Carcharocles megalodon (the roots of its species name are Greek and, appropriately, mean “giant tooth”).  I didn’t find any meg teeth that day, but did find an array of wonderful fossils.  The bone in this bag was one of them but, over the years, I’d forgotten all about it.  It fell victim, in part, to the lapses of an aging memory and to how I curated my collection. 

The reason for all of the baggies among which this particular fossil bone lay hidden is a choice I made early on:  obsessively record when I collected a fossil.  The drawers were organized primarily by the location where fossils were found and secondarily by the kind of fossil (e.g., tooth or shell).  As a result, if I had many fossils from a particular location (certainly true for those I visited repeatedly over the years) and, even if many of the fossils were largely indistinguishable (to wit, any one sand tiger tooth is much like any other – identifying genus and species is often a chore), the specimens ended up in a multitude of bags distinguished only by collecting date, a piece of information that, in retrospect and despite the pleasant memories stirred up by what took place on the date on this bag, is largely meaningless.

When this piece of bone reemerged, after being long lost in the collection and in the mists of my memory, I took what had been the usual first step in identifying a fossil from the Lee Creek Mine:  page through Neogene and Quaternary Fossils of North Carolina:  A Field Guide, prepared by Richard Chandler (text) and John Timmerman (illustrations), published by The North Carolina Fossil Club.  Although the copy I currently have at hand is the 2011 revised edition, I once owned the 1994 edition of this guide and must have used it in 2008 when I got home from the mine.  This is an excellent and very handy publication; each of the fossils covered is nicely illustrated and identified.  There, on page 31 of the current edition, under the title Common Bony Fish Fossils, is a drawing of the very fossil in my bag along with several others.  (The image below of this portion of page 31 is included here with the kind permission of the guide’s authors.)

The spindle-shaped fish specimen in question is identified as a ventral postcleithrum.  The other fossils depicted are cited as suboperculum, preoperculum, and operculum.  The placement of the label “Sphoeroides hyperostosus (Pufferfish) Gill Plates” is a bit misleading because only the latter three bones, not the postcleithrum, are gill plates.  What is true is that all four of these fossils are abundant in the Lee Creek Mine and all come from S. hyperostotus (more on that below).  (In a private communication, one of the authors noted that a future edition would address the issue of that label placement.)

The effort to identify this once lost Lee Creek fossil exploded into a host of related (and semi-related) questions and issues.  Among the most immediate:  Pufferfish?  What is a ventral postcleithrum?  What are gill plates?  Doesn’t the fossil illustrated in the upper left of this display, identified as a suboperculum, look familiar?

Zoologist Katherine Ellott Bemis writes that “pufferfishes and their relatives are some of the most diverse fishes in terms of anatomy and natural history.”  (Pufferfishes and Their Relatives, Smithsonian, National Museum of Natural History, Ocean Life, January 2023.)   Their diversity extends to size, color, and defense mechanisms.  They are well known for their ability to defend themselves by inflating their body and extending spines, and for the lethal toxicity of some species.

In bony fish (which include pufferfish, extinct and extant), a gill plate is a bony flap, called the operculum, that covers the gills on either side of the fish, affording protection for the gills and aiding in respiration.  Generally, the operculum is a mosaic of several bony pieces (the opercular series) consisting of the preoperculum, suboperculum, interoperculum, and operculum.  I assume this last bone carries the same name as the full array of bones because it’s the one in the series that actually covers the gill chamber.

I should note that, after plowing through many detailed and tedious research articles about fish gill plates, I found the most cogent summary to be a piece by a former librarian and “pet enthusiast”  Kathryn Copeland titled What is the Function of the Operculum on a Fish?  It appears on the website:  ZooNerdy and was updated October 21, 2023.  I regret that she did not cite the underlying sources for the information she conveys.  That said, her piece squares with what I managed to understand from the research literature I plowed through.

I am puzzled about the postcleithrum which is not part of the opercular series and so is not a gill plate.  I believe it to be part of another series of bones running from the area of the pectoral fin to the cranial area.  My effort to find an accessible discussion of this bone and its function has so far been fruitless.  

Sphoeroides hyperostosus, the species cited by the North Carolina fossil guide, was named in 1992 by J.C. Tyler et al. based on a partial skull found at the Lee Creek Mine in the Yorktown Formation (Pliocene Epoch).  (A New Species of Sphoeroides Pufferfish (Teleostei: Tetraodontidae) with Extensive Hyperostosis from the Pliocene of North Carolina, Proceedings of the Biological Society of Washington, Volume 105, Number 3, 1992.)  This was a particularly important find because several of the bones in the skull were hyperostotic (i.e., swollen), a condition that prompted the authors to give the fossil its species name.  Tyler et al. assigned all of the kinds of bones depicted in the illustration from the North Carolina fossil guide to S. hyperostosus, distinguishing ventral postcleithrum bones from opercular bones.

The disarticulated hyperostotic opercular bones that are so common at Lee Creek Mine can reasonably assumed to be from S. hyperostosus because of their similarity to those from the Lee Creek skull.  We presume that the disarticulated ventral postcleithra from Lee Creek Mine are also from S. hyperostosus because it is the only species of Sphoeroides (and tetraodontid) known from Lee Creek and the disarticulated ventral postcleithra in general are similar to those of most species of Sphoeroides. (p. 463)

Until the work by Tyler and his colleagues, identification of source of these fossils had been problematic.  Now it was shown that all of these swollen bones were from an extinct species of pufferfish and that the condition of these bones was, as the authors concluded, “normal.”

As for my sense that I somehow already knew the suboperculum, it was a relief when, after some searching, I found a small plastic case (shown below) in the back of a drawer in the wooden cabinet that houses some of my better small fossils.

Of course, would it not have been logical and appropriate that, when these suboperculum bones graduated to the wooden cabinet housing my nicer pieces, they would have carried labels delineating not just collecting location and date, but also genus and species (given that I presumably knew them)?  But, no.  As the picture clearly shows, these two fossils were labelled simply “NS10-11.”  No other information, not even the bits I was most consistent in assigning to my specimens.  Tyler et al. had stated that S. hyperostosus was “known only from the Lee Creek locality” (p. 463), so that was most likely the source of these fossils.  Still, the differences in color and greater density that the black specimen exhibited raised real questions about its origin that only a deciphering of the alphanumeric data on the case could answer.  That process, described below, borders on being a separate shaggy dog story.

It took awhile but I finally recalled that at some stage, when I attempted to organize my collection digitally, I fed data into the Trilobase application (versions 6 and 7) using “NS” for “non-shark” (as these fossils certainly were).  Since nothing comes easily, that foray into the digital world was at least one, if not more, computers ago, forcing me to find backup disk drives for those earlier PCs.  Eventually I did come upon a file identified as “non-shark,” but at this point I couldn’t open it because I had no functioning version of Trilobase application.  After a bit more screwing around, I downloaded a copy of the program and opened the file.  There they were, entries for NS10 and NS11:

Don't bother trying to read the text of these entries (though they are quite legible inside the program), I will transcribe the relevant information from each of these pages.

For NS10, I wrote the following description:

Height Dim:  5/8"
Pufferfish suboperculum:  part of opercular series of bones that make up what are called gill plates
tan and very light weight, repaired

For its location, I wrote:

this was on the surface at Lee Creek and just seemed familiar -- I had already found a ventral postcleithrum (had no idea what it was) but recognized the shape -- it's also one of the gill plate bones

I entered a personal note for this fossil:

first fossil repair attempted

The date of collection was 10/12/2008. 

For NS11, I entered this description:

Height Dim:  3/4"
Pufferfish suboperculum (see description for NS0010)
this is black, passes clink test -- feels like rock -- NS10 doesn't which still has a porous bony feel to it

I noted its location as:

Green Mill Run - screening in the stream

I also entered a note on this specimen:

this struck a chord -- so similar to what I found the day before at Lee Creek 

The date of the collection was 10/13/2008

How could I have forgotten how incredibly useful the Trilobase program was?  Too bad I didn’t use it religiously.

The dates on which these two subopercula were found are telling.  It’s not really surprising that my collection contained specimens found on October 12, 2008, at the Lee Creek Mine, and specimens collected the next day at the Green Mill Run site at Greenville, NC, some 50 miles from the mine.  (The stream actually appears to be named Greens Mill Run, but I never heard it called that.)  Once collectors had made the trek to Lee Creek, nearby fossil sites were fair game.  Doing Lee Creek and Green Mill Run back to back was par for the course.  The latter offered a very different collecting experience.  That Monday, I walked the streambed, shoveling and sifting gravel in pursuit of teeth, and I was alone.  Here’s a picture from that day.

What is surprising to me is that the same kind of fossil I found at the mine, turned up at a site 50 miles to the northwest.  I’m inclined to say:  So much for the notion that S. hyperostosus is unique to Lee Creek.  That said, where exactly any Green Mill Run fossil actually originated is uncertain.  Fossils found here are a mixture of ones from the Cretaceous Period forward to the Pliocene Era because the stream cuts through various geological strata.  One of these is the Yorktown Formation, the same one yielding all those S. hyperostosus fossils at the Lee Creek Mine.

The Trilobase entries that I unearthed offer more evidence that the clerks in charge of my memory had misfiled other pieces of information related to these fossils.  When I created the entry for the Lee Creek suboperculum, NS10, I already knew that it was associated with a fossil I had found the same day, a ventral postcleithrum.  Clearly, I had done some research on both, beginning with the earlier edition of the North Carolina fossil guide.  And even more disillusioning, I separately uncovered evidence that, shortly after the Lee Creek foray, I engaged in a long, detailed exchange of messages on a fossil listserv, a discussion that covered these very fossils, their origin and identification.

When I lay out all that I learned recently about what happened and didn’t happen to these three fossils in my collection, my reaction is:  WTF?  I should be subject to a bill of particulars over failures in my stewardship of fossils.

Here are the most salient parts of that charge:  The majority of my fossils ended up in a seemingly limitless multitude of plastic baggies labelled with only the barest of information associated with any one of them.  Yes, I identified the postcleithrum bone collected at Lee Creek, but I never labelled it with that information, noting only location and date collected.  I also did not create a Trilobase entry for it.  Further, the baggie with that bone “disappeared” into one of a number of plastic drawers full of Lee Creek material in myriad bags.  As a result, it was separated from the two suboperculum fossils that might have given it some context.  In addition, at one point, I obviously felt that the two suboperculum bones were important because I created entries for them in Trilobase and engaged in an extended give and take on a fossil listserv about them.  Nevertheless, as further evidence of my malfeasance, when it came time to put them in the cabinet with the “good” stuff, I simply slapped an “NS10-11” on their case, as if that would make sense to someone who might come upon them later, including me.  This action was taken despite the fact that the Green Mill Run specimen may actually have some broader scientific interest because it belies the notion that S. hyperostosus is unique to Lee Creek.  (On this issue, see the note below.)

All of this is so bittersweet.  Among the sweetness are some good memories of fossil collecting trips and, I’ll admit, some pleasure from the research I pursued for this post (though it was often over ground I’d trodden years ago).  The bitterness comes from regret over those decisions made back when and the slapdash way I took care of my specimens.  That my recollection of the specifics associated with this trio of pufferfish fossils has proven difficult for my mental clerks to recover is quite disheartening.

I guess these are among the usual emotions stirred up by downsizing. 

The online Paleobiology Database indicates two locations at which the extinct species S. hyperostosus has been found:  Lee Creek Mine in North Carolina and the Austin Sand Pit in South Carolina.  The only evidence for the latter is the mention of this species in a list of the fossil vertebrates purportedly found in the Pit.  The Paleobiology Database’s source citation for this list is a 2018 research paper in which I found with no description of either the origin or the process for compiling the list.

No comments:

Post a Comment

Nature Blog Network