Triarthrus Trilobites

These rare specimens come from  a quarry in New York where Triarthrus trilobites are found with preserved appendages, antennae and other organs.  The preservation of these specimens is astounding, and the skillful preparation that is required to reveal these features can take hours and hours of slow, painstaking work.  The state of preservation and the skill of the preparator rival even the finest Bundenbach Trilobites that I've ever seen.  The Bundenbach specimens don't even come close in micro-preservation!! These specimens average in length at 1 cm.   The trilobite specimens are colorfully preserved in glittering gold pyrite by mother nature. 
 
"Modern and extinct arthropods, including trilobites, have an outer carapace or shell, made from a complex form a calcite incorporating proteins and polysaccharides, often referred to simply as chiton.  For ease of understanding, a trilobite’s dorsal shell exoskeleton can be compared to the shell of a crab for some species, or a bit softer for others.   The ventral (underside) membrane of the trilobite, along with its legs and antennae, were not hardened as the dorsal surface.  These soft parts had a similar consistency of the dangling legs of a shrimp and their rather soft antennae.  When a trilobite is fossilized these soft tissues have a very slim chance of preserved, much less than that of the hard-calcified exoskeleton. To quantify the rarity of soft tissue preservation, I would say with confidence, that only the hard, calcified dorsal exoskeleton is seen in a percentage greater than 99.9% of the time.  That means of all the trilobites ever fossilized over the course of several hundred million years, less than .01% of these animals show evidence of soft tissue preservation.  This extreme rarity expressed in percentage value is shocking.  From an evolutionary standpoint the soft tissues of early animals such as trilobites is an opportunity to understand how organisms evolved to meet challenges in ever changing environments, and ultimately avoid or succumb to extinction."
 
These specimens are not from the Beecher Beds, but are from a new locality with a limited number of initial specimens available for sale before it goes under control of the academic community.
 

Last Modified 04/11/2008

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(Click Photo to Enlarge)

Name:  Gravicalymene magnotuberculata
Geologic Age: Middle Ordovician (445 Million Years Old)
 Stratigraphic detail:  Sugar River Formation, Trenton Group
 Location:  New York

Comments:   This is a spectacular small plate of multiple (4 total) very rare Gravicalymene magnotuberculata from the Sugar River Formation, Trenton Group, New York State, Middle Ordovician.  Gravicalymene magnotuberculata is one of the rarest North American trilobites, found in only 2 or 3 locations in New York State.  The most complete Gravicalymene magnotuberculata on the plate is the lateral, lying on its side with a slight curve to the thorax.  This trilobite measures 4cm (1.6 inches) with the curve, so outstretched it would be a bit longer, but you get the idea.  There is a dorsal next to it, and incredibly a ventral lies on top of both trilobites to the rear, its body contorted somewhat, but the head, segments and pygidium are present and well defined.   Beneath the plate on its underside is yet another partial of a once complete bug, a ventral also with a very well defined cephalon.  These trilobites are large for the species.

 

This is a new locality that was discovered last season.   These Gravicalymenes also occasionally produce sporadic examples of pyritized soft tissues such as legs and antennae, similar to the Triarthrus examples on my site.  This small plate is one of those examples.

 

The exoskeletons of the Gravicalymene's are calcified, yet the soft tissues are preserved in framboidal pyrite.  This selective preservation may be due to the fact that the sulphate reducing bacteria responsible for the framboidal pyritization could not secrete enzymes to break down the thick-shelled exoskeleton, perhaps a very hard modified chiton.  The soft tissues on the other hand may have been a mild unmodified chiton, easily reduced by the bacteria.  The soft tissues on this specimen are nothing spectacular but still present.  One leg on the ventral on top of the other two trilobites shows it's well-defined 'spike' for manipulating prey.  Another leg near the genal curve shows nice segmentation.  The soft tissues are clearly highlighted in the pictures.  THE PLATE HAS BEEN REPAIRED IN SEVERAL PLACES, BUT NO RESTORATION. 

 

The plate is important enough that we saw fit to put it through some in depth photography when it was finished being prepared.  Most of the pictures were shot in a dimethylbenzene (xylene) chemical bath for definition of the carapaces and soft tissues and hence the different colors.

Gravicalymene Trilobite 1 - Price $275.00