Saturday, January 14, 2012

Conrad's Description of Platyostoma ~ I Like It, But What Do I Know?

Paleontology to me is more than just about the fossils, it’s also about the people who did, and do, the science.  It’s their stories that I uncover in an action that parallels the discovery of a fossil in the field.  Just the act of expanding my collection, whether I found the new fossil myself or not, precipitates a taxonomic exploration of its scientific name that inevitably becomes about people.

Here are several pictures of a recent acquisition, a small Silurian gastropod from the Waldron Shale, near St. Paul, Indiana, a member of the genus Platyostoma.  And so the door opened.

(That's a small brachiopod attached to the snail.)

For a paper read 170 years ago this next Wednesday, January 18th, before the Academy of Natural Sciences of Philadelphia, Timothy Abbott Conrad (1803 – 1877) penned a succinct description of a genus of Silurian gastropod he named Platyostoma.  (Conrad is not new to this blog – more on that below.)  Though the paper, titled (somewhat tersely for its day) Observations on the Silurian and Devonian Systems of the United States, with Descriptions of New Organic Remains, was not particularly earthshaking, its description of Platyostoma is, I think, rather fine.  (Journal of the Academy of Natural Sciences of Philadelphia, Volume 8,  Part II, 1842.)

Conrad was, it would appear, a somewhat tortured soul, suffering physical and mental ailments for much of his life.  Nevertheless, he fashioned a prominent career in paleontology and his work has lived after him.  His pedigree may have helped his paleontology both in terms of nature and nurture.  (I cannot hazard a guess of its import for the other aspects of his life.)  His father, Solomon White Conrad, a printer, had a deep interest in natural history and was appointed Professor of Botany at the University of Pennsylvania.  Conrad père also served at one juncture as the librarian of the Academy of Natural Sciences and articles of his appeared in the Academy’s Journal.  (The Mineralogical Record, Biographic Archive.)

Though Conrad fils seems never to have attended college, he soon followed in his father’s footsteps in the sciences, first publishing in the Journal in 1830.  For a brief overview of Conrad’s life, see Ellen James Moore’s article titled Conrad's Cenozoic Fossil Marine Mollusk Type Specimens at the Academy of Natural Sciences of Philadelphia (Proceedings of the Academy of Natural Sciences of Philadelphia, Vol. 114, 1962).  Some aspects of Conrad’s life story were covered in a previous posting on this blog which focused on one of the quirky, though justifiable, aspects of the process of constructing and applying new scientific names to specimens.

The emphasis in that prior posting was on Conrad’s apparent carelessness in fashioning the name Pterorytis for a Miocene gastropod.  That proclivity in his naming of specimens figures a bit in the story recounted in this current posting, but it’s not the heart of the matter here.  Rather, I really set out just to salute the few lines of text he wrote to describe the shells of the gastropod genus Platyostoma.  The more I have considered this description and applied it to the sole specimen of this genus in my collection, the more I value it.

Here, then, is Conrad’s description of the genus en toto from his 1842 article:
Shell subglobose; spire short; aperture very large, suborbicular, dilated; labrum joining the body whirl at right angles to the axis of the shell.  (p. 275)
“Succinct,” yes, but not necessarily “immediately accessible.”  So, here it is again with a few explanatory notes for some of the terms:
Shell subglobose [not completely spherical]; spire short [the spire consists of all of the whorls above the body whorl which is the last and largest]; aperture very large [the aperture is the opening at end of the body whorl], suborbicular [not completely circular], dilated; labrum joining the body whirl at right angles to the axis of the shell [the labrum is the outer lip around aperture, the axis is the center line around which the shell coils].
My annotations were informed by Invertebrate Fossils by Raymond C. Moore, et al., (1952, p. 284 – 285) and the web-based An Illustrated and Cross-Referenced Glossary of Malacological and Conchological Terms, prepared by Paul S. Mikkelsen.

Among the illustrations with Conrad’s 1842 article is one depicting three species of Platyostoma.  They are figures 5 – 7 in the illustration below (ignore figure 8).

I am impressed (perhaps too easily) when I match my specimen or the three species illustrated by Conrad to his 1842 description of the genus.  To wit:  the shell’s not a perfect sphere; its spire is small (very much dwarfed by the body whorl); the aperture is a gaping, not quite circular hole (clear in Conrad’s illustration, and I presume it is also for my specimen, though its aperture is somewhat hidden in matrix).  A bit harder to see is the angle of intersection between the shell axis and the plane of the labrum.  In the picture below, I’ve taken a stab at showing that intersection in one of the earlier images of my specimen.  The angle may not be 90 degrees but it’s relatively close.

Perhaps I should have let it rest there:  Conrad captured the essence of the genus and I can use his description to reassure myself that what I’ve added to my collection is from the Platyostoma genus.

But I cannot resist picking at seams.  Ellen James Moore’s article, mentioned earlier, suggested quite strongly that one of the very attributes I applaud in this description – its terseness – may be ranked among Conrad’s taxonomic faults.  She wrote, “[H]is descriptions are sometimes very brief and occasionally illustrated by unclear drawings.”  (p. 26)  Later, she cited “his often all too brief descriptions of species.”  (p. 27)

The risk I can see in a short description is that it may not be adequate to distinguish among several morphologically similar genera or species.  That squares with my reading of the International Code of Zoological Nomenclature (Articles 11 - 13, and Glossary) which requires that a publication in which a new genus or species is named include a description.  It defines a "description" as “A statement in words of taxonomic characters of a specimen or a taxon.”  A character is “Any attribute of organisms used for recognizing, differentiating, or classifying taxa.”  It would seem that the operative requirement is that the description adequately distinguish the newly named taxon from all others.  Though the Code differentiates between names published before 1931 and those published after 1930, there doesn’t seem to me (perhaps in my ignorance) a categorical difference in what constitutes the required description in either instance.  Brevity itself doesn’t seem to matter, it’s what is accomplished in that brief description that does.

Is this a problem with Conrad’s description of the Platyostoma?  I really don’t believe so since it appears to me to identify critical features of the shell.  So, the description seems fine, but what do I know?  Proof in the pudding?  Though not really a gauge of the adequacy of the description, Conrad might point to the fact that the name he gave it has survived 170 years, and in 2004, it appeared in the masterwork Classification and Nomenclator of Gastropod Families, edited by Philippe Bouchet & Jean-Pierre Rocroi, Malacologia, Volume 41, Numbers 1 and 2, p. 134.

Ah, yes, the name.  Unfortunately, it’s T.A. Conrad we are engaged with here, so things are never as simple as one might hope.  Consider the name he gave the genus, Platyostoma.  It was derived from two Greek roots:  platy meaning “broad, flat” and stoma meaning “mouth.”  (Donald J. Borror, Dictionary of Word Roots and Combining Forms, 1960.)  It's a great name, very appropriate, but, in the scientific literature, the name of this gastropod genus is often spelled Platystoma – without the first “o.”  I believe we have Samuel Almond Miller (1837 – 1897) to thank for that.  Miller, a lawyer and newspaper editor, was, in addition, a much published amateur paleontologist and editor of the Journal of the Cincinnati Society of Natural History, and the Cincinnati Quarterly Journal of Science.  Many of his articles appeared in his own journals.  (A brief bio appears in William Charles Miller’s Trace Fossils:  Concepts, Problems, Prospects, 2007, p. 26-27.)

In his 1877 book, The American Palaeozoic Fossils:  A Catalogue of the Genera and Species . . . . (and the title goes on and on, nothing terse about it), Miller included an introductory piece written by a Professor Claypole of Antioch College, titled Construction of Systematic Names in Palæontology.  In it, the good professor observed,
The connecting vowel o is admissible by Greek usage in all declensions, . . . , except where the first part of the word is an adjective ending in – ys, it is shorter and at the same time consonant with classic usage to employ no connecting vowel at all; thus, . . . Platystoma , . . . [is] better than . . . Platyostoma, . . . .” (p. xii) 
Following the lead of his expert, in this volume Miller summarily changed Conrad’s original spelling and the battle began, with skirmishes continuing up to today.

I cannot pretend to know why Conrad joined the two roots with an “o” but I don’t think it should have consequences for the naming of the genus.  The International Code of Zoological Nomenclature identifies situations in which misspellings must be corrected (Article 32.5).  Clear evidence in the original publication of an inadvertent error (such as a “lapsus calami” or a slip of the pen) requires correction, but “[i]ncorrect transliteration or latinization, or use of an inappropriate connecting vowel, are not to be considered inadvertent errors.”  (32.5.1)  And even Miller’s own expert characterized Platystoma only as better than Platyostoma, not the former correct and the latter incorrect.

Nevertheless, though Bouchet and Rocroi tried to dispose of the issue by characterizing the dropping of the “o” as an “unjustified emendation” (p. 134), if history is any guide, that wont do it.  Seems a shame given how much I like Conrad’s description of the gastropod genus Platyostoma.

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