Hill Annex Mine Fossil GalleryFossils From the Cretaceous Era Coleraine Formation in Calumet, Minnesota |
2017 #1 |
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Ctenoid Fish Scale Diagram
Image Source https://www.researchgate.net/figure/Surface-view-of-body-scale-showing-different-structures_fig2_259450297
Jawad, Laith. (2013). Comparative scale morphology and squamation patterns in triplefins (Pisces: Teleostei: Perciformes: Tripterygiidae). 16.
Originally appearing in Lippitsch, E. (1992). Squamation and scale character stabilityin cichlids, examined in Sarotherodon galilaeus(Linnaeus,1758) (Perciformes, Cichlidae). Journal of Fish Biology41:355–362.
This fish scale impression may preserve the ctenii structures.
Preview Image is 8% reduction of the 200X image.
Click image for 50% view of 200X Magnification
Potential Ctenii impression area.
Preview image 50% size from 77X Magnification. Left light illumination.
Click image for full size.
Another view with right side lighting. This is a reduced and cropped section of a 335X image. See full image for scaling information.
Fragments of scale material. This is a reduced and cropped section of a 335X image. See full image for scaling information.
Growth rings detail - Preview image 20% of 335X Magnification.
There appears to be a fragment of the original scale material near the size scale bar.
Other fossils in this rock
Gastropod. Note the large purple crystals this has. It is surprising given how granular parts of this rock are that was able to preserve the micrometer size structures of a fish scale.
Plant stem
In Situ photos
The rock fragment that this fish scale is part of is made of a black sandstone. This site was discovered by a lone boulder of this material with snail fossils in it. The fossils in other areas of hill annex tend to be in blue green shale conglomerate. These rocks are black and brown probably due to high iron or hematite content. This area produced serveral other large fossils of ammonites and large mollusks made out of the same type of rock. The rocks buried in the sand had minimal erosion. The fish scale was found near the boulder as I recall - though at the time I did not know it was a fish scale. I thought it had an odd texture mostly and it was not particularly notable - at most it was an eroded gastropod. See field photos from that area.
3D surface views
Part of the reason I look at the 3D surface view is to see how level I got the scale under the microscope.Scale impressions are not completely flat but I try to keep the tilt to a minimum for the photos.
