Fossil Identification Loupe: Ammonites to Trilobites
Fossil identification is central to paleontology which is the study of living things now long dead & preserved in sedimentary rock. Most of these plants, animals and microbes are extinct but some have descendants that are alive today. Comparing the past and the present puts paleontology at the intersection of biology and the study of rocks and minerals typically associated with geology. Both require magnifiers for field work and the requirements are discussed below.
Trilobites are among the most common of creatures that students learn about in fossil identification. They were highly successful animals from the early Cambrian before going extinct in the Permian. Trilobites were very diverse with over 10,000 species and they roamed the Earth for roughly 270 million years. Trilobites are classified as arthropods which include the crustaceans and insects.
Fossilized trilobites visible to the naked eye. Since there were over 17000 species, a 10-15X magnifier is useful in distinguishing features.
Fossil Gastropod Identification
“Polished Tyndall Stone from near Winnipeg, Manitoba. Geologically this is the Selkirk Member of the Red River Formation, a tropical, shallow-marine limestone of Late Ordovician in age, about 450 million years old. The Tyndall Stone contains many fossils, such as these two big snails. They belong to Maclurites. This is part of the presentation wall that is the memorial to geology students from the University of Saskatchewan who fell in World War II. The wall is used a lot in teaching, and the students are expected to examine all the features using their hand lens”. Photograph & text by Prof. Brian Pratt.
Photograph by Prof. Brian Pratt. University of Saskatchewan. A penny in the upper left hand corner to give an idea of scale.
Fossil Identification Magnifier
Prof. Pratt: “Yes, generally 10X is enough for field work but 15X is sometimes a help, depending on the fossils (if they are very small) and the observer’s experience. I’ve had positive comments from students who have continued on and have more experience.
A wide lens (30mm compared to 15-21mm metal doublets or triplets) is ideal for looking at fossils in the field or the lab because it lets in lots of light.”
This 30mm triple folding magnifier is an economical field tool for identifying trilobites, crinoids, brachiopods, stromatolites, ammonites, etc. & even fossil traces.
Doublets/Triplets vs Double/Triple Lenses
At first glance these appear to be the same thing but they are not. A doublet has 2 lenses that have been cemented together, a triplet has 3. These magnifiers compensate for light refraction as seen with prism and sunlight. Red, green & blue light disperse at different angles. A doublet corrects for 2 of these colors, a triplet 3. This can be important if you are studying minerals and crystals as geologists do.
A double or triple lens magnifier like the one above only increases magnification when the two or three lens are stacked. This is sufficient for studying fossils or reading fine print or hunting for plant mites.
About Prof. Brian Pratt
Dr. Pratt is a full professor in the Department of Geological Sciences, University of Saskatchewan in Saskatoon. More in his own words:
“Here is a photo of me in action a few years ago in the Mackenzie Mountains south of Norman Wells, NWT. My hand lens is concealed by my hand and by chance it actually is not an Indigo one but I have another which is. I usually bring a couple along in case I lose one and yours would have been in my gear.”
Prof. Brian Pratt, Univ. of Saskatchewan, doing field field work.