Friday, July 30, 2010

The importance of localities

Fossils have little scientific meaning if they arrive in a collection with no information. Identifications can be made at any point in time. Photographs can be taken, accession lots can be assigned. If no locality information has been gathered or retained, then the fossil is often nothing more than a pretty specimen. If there are any fossil collectors out there reading this, I beg you - please note where your specimen is from stratigraphically and geographically. Even if you are not sure of the exact unit, note the lithology. Is the rock grey, black or brown? Is it hard like a limestone or does it break apart more easily like a shale? Where in the world is your rock from? A city or town is a good place to start, but try to be more specific. If you have a GPS unit, use it (but be sure to note the datum and uncertainty contained within your unit). If you don't have a GPS unit, don't despair! Try marking out your fossil locality on a USGS 7.5" topographic map. You can download them here. Using businesses as landmarks can get complicated because businesses come and go. If you want to use buildings as landmarks, use buildings that will be around for some time (and will be plotted on maps) like the courthouse or town hall. Note when the specimens were collected as well. Town hall may be in a different place fifty years from now, but if the specimen was collected on a known date, the location of the town hall at that time can be determined.
Having delivered my collecting tips for the week, I leave you with some photos of specimens with some (although definitely not the best) locality information.

Wednesday, July 21, 2010

Clionid sponges

A number of modern and fossil sponges made their homes inside the shells of other organisms. Rather than taking an empty gastropod (snail) shell like a hermit crab, these sponges literally move into a shell. Clionid sponges use a combination of physical and chemical abrasion to create openings in shells. They then spread out throughout the internal structure of the shell to create an extended home for themselves. I often imagined these sponges waiting until an organism dies to create the network of galleries, but it seems this isn't always the case. A detailed study published in 2005 by Stefaniak et al. in the Journal of Experimental Marine Biology and Ecology examined the effects of clionid borings on living Littorina snails. They found that the snails reacted to the invading sponges by thickening the interior lining of their shell (thus reducing their living space). In addition, the shells were much weaker structurally after the sponges bored out their galleries.

YPM 11323
To get an idea of what these sponges do, here's a pectinid bivalve that has been extensively bored by clionid sponges. Since these borings occur on both the interior and the exterior of the valve, this pectinid was likely dead prior to the borings (at least on the inside).

While this may not seem particularly damaging at a glance, a look at the cross-section of another bored shell shows what is really going on. Much of the structural integrity has been worn away by the sponges relentless chemical and physical attack. On the plus side, though, the sponges get a safe home in a nice hard substrate.

YPM 11324

Wednesday, July 7, 2010

A prominent early dealer

August Krantz began his fossil shop in Freiburg, Germany in 1833. Through personal relationships with important scientists and collectors of the day, August Krantz amassed a sizable and diverse collection of fossils. 

Friedrich Krantz (pictured - photo from the Krantz website) was well-known to fossil collectors and museums alike throughout the late eighteenth and early nineteenth century. He took over as head of the Krantz fossil and mineral firm in 1891. He sold specimens to many institutions including the Yale Peabody Museum, Harvard's Museum of Comparative Zoology, and the National Museum of Natural History (Smithsonian).

Dr. Krantz developed numerous special collections of fossils that were used around the world as teaching aids. Dr. Krantz and his employees traveled the world scouting out interesting localities and collecting fossils to replenish the firm's stores.
Many of the specimens in the Peabody's collection where obtained by Charles Schuchert (an early curator who I will discuss in detail in another post). The "Krantz" specimens are all marked with a small green sticker bearing a handwritten number. This number corresponds to a catalog that was included in the shipment.

The Krantz mineral and fossil firm is still in business and can be found here. Today the firm carries a wide array of fossil material and fossil casts, and it is still used by personal collectors and large institutions.