Trilobite tribulations

Finding or buying fossils is the easy part. Identifying the creatures is a question of patience and endurance, but it seems to be worth the tribulations.
By Mike Molloy, Munich.

In an attempt to neutralise the ’black hole’ threatening Upper Bavaria, following the year end exams in 2000, I decided to try to identify more exactly, some of the unknown or only vaguely known fossils in my modest, but growing collection. In particular, I was unhappy about the identities of the three trilobites which I have acquired in the last two years, so armed with two books on fossils and the Internet, I set about finding order, family and species names for all three.

I think that a few remarks are necessary about the quality, quantity and completeness of the information from my three sources. Of the two books that I have access to, one is a reference book, originally written in Czech, then excellently translated into German, using samples from the palaeontology collection of the National Museum in Prague. Its weakness is that the range of fossils covered is limited to those commonly found in central Europe and the number of different trilobites on offer is limited to about 45, which is somewhat restricted for the eight orders, with some 15,000 recognised species, worldwide. The second book is a paperback, which gives the impression that the range of fossils covered is greater than that of the reference book, in fact as far as trilobites go, this is not the case. Its main weakness is that the number of photographs of specimens is very limited, due to the lack of space and the attempt to counterbalance that by describing the differences between those species photographed and those which are not, fails miserably as far as I am concerned. I’m sure everyone knows the strengths and weaknesses of the Internet as a source of information, simply using a key word such as ‘trilobite’ to interrogate the Net will engulf you in about 145,000 entries, equally unsatisfactory would be an attempt to use each recognised species name as a key word, in an attempt to find 3 from about 15,000.

Two of my trilobites possessed primitive ‘birth certificates’ when I purchased them, the third came without any identity papers at all, as such, I decided to start investigating the two with papers first. One, purchased in Munich, was described as a Phacops from Morocco, and the second, purchased in the UK, simply as a Phacops. My Moroccan Phacops was identified quickly, two good photographs, together with a description and typical dimensions found in the reference book gave me the information I needed for the Internet and the ‘Google’ search engine supplied the rest. Amongst other websites, it pinpointed an excellent French site dedicated to North African fossils, the photograph they displayed could have been a twin of my Phacops latifrons, probably from the lower or middle Devonian, whose full family tree would seem to be:

Order: Phacopida
Suborder: Phacopina
Superfamily: Phacopoidea
Genus: Phacops
Species: latifrons

The second ‘Phacops’ was more of a problem, indeed, the search for its identity was to last about four months and cost a fortune in Internet fees, so I decided to attempt to identify the unnamed and stateless, but very fine specimen purchased at the Munich Mineralientage a few weeks earlier. My knowledge of trilobites was to say the least, very basic when I started these investigations, however, it soon became clear that without a systematic approach and without paying great attention to detail, any success in identifying all three beasts would be purely coincidental. How right this turned out to be. By this time, I had a good overview of the Internet websites which were worth exploring and I began to unashamedly use or misuse some of them, in particular, the award winning website of Dr. Sam Gon.

By now, I was beginning to apply some basic methodology to my search, such as counting the number of segments in the thorax and pygidium and in particular, noting the general layout of the cephalon, shape of the glabella and the position and shape of the eyes. All of my specimens have 14-15 thorax segments and 4-5 pygidium segments, which made me think that all three may have been from the same order, this proved subsequently to be false, but it set me on the correct track to identify the unnamed specimen. By now I also had a fairly comprehensive list of species, sorted by order and family, from a website published by the TU Clausthal-Zellerfeld, this together with Sam Gon’s website and my lucky guess soon identified my unnamed species as Ondontochile hausmanni, from the lower Devonian with the full family tree, again courtesy of Sam Gon, of:

Order: Phacopida
Suborder: Phacopina
Superfamily: Dalmanitoidea
Genus: Odontochile
Species: housmanni

This left the UK ‘Phacops’ still to be identified and because of the same number of thorax and pygidium segments that it shared with the other two Phacopida, I was inclined to believe the rather scruffy ‘birth certificate’ which came with it. Unfortunately, although the thorax and pygidium of this specimen are well preserved, the cephalon is not, there are no eyes and the only remaining feature easily distinguished is the shape of the glabella. If I had paid attention to this earlier, I would have saved myself a few hours at my PC, waiting for a response from the Internet. Eventually, after much trial and error, I noticed that the glabella of my specimen narrowed towards the front and that the only suborder of the Phacopida where this is the case, is Calymenina. This ‘limited’ the search to about 9 Genera, none of which matched my specimen and I was forced to scrap the ‘birth certificate’ and start again, with the only information that I had regarding the size and shape of the specimen, the number of segments and the shape of the glabella.

By now, several weeks if not months had passed, but finding out the true identity of the ‘imposter’ left me no peace and I returned time and again to Sam Gon’s website. One other detail that I had overlooked was the general shape of the thorax, some species of trilobite were more streamlined than others and by looking for the right combination of glabella shape and thorax shape, together with the number of thorax segments, at least narrowed the field down to about 8 superfamilies.

It was at about this stage of my investigations when coincidence triumphed over incompetence and on page 233 of the book that I had given myself for Christmas, Trilobite!’ Eyewitness to Evolution by Richard Fortey, I found what could also be the twin of my imposter, Elrathia kingi . Again, I can recommend this book as an excellent read, even for the non-trilobite freaks. Sam Gon’s website produced the rest of the information that I had been looking for, Elrathia kingi ’s full family tree as follows:

Order: Ptichopariida
Suborder: Ptychopariina
Superfamily: Ptychoparioidea
Family: Ptychopariidae
Genus: Elrathia
Species: Kingi

Note: 'kingi' is often and possibly more correctly spelt 'kingii'

If Elrathia had been an exotic, extremely rare specimen, I suppose I would have felt a little better about my inability to identify it. In fact it is one of the most common species of trilobite that ever existed, which accounts for the give-away price that I paid for it, about £5.00 if I remember rightly. Do not be misled into thinking that the tribulations that this imposter caused me have dampened my enthusiasm for more of the same. Identifying fossils which you have bought, anonymously, is second only to identifying fossils that you have found yourself and accounts for most of the fun of collecting them in the first place.

Elrathia kingi
Elrathia kingi

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