Microfossils & Microfossil thin sections

My largest error photo – a microscopy photo of fossilised coral from Oklahoma – 543.87 megapixels!

Microscopy of Caninia torquia fossilised coral from Oklahoma. I used the Zeiss IM microscope, x4 objective, plane polarised, Bresser Mikrocam 9.0 camera.

Photos taken on 26/11/2017 – 100 photos stitched together using Microsoft Composite Editor.

Final image = 14704 x 36988 pixels (543.87 megapixels)

The photo shows the structure of the coral, divided into rectangular areas by dividing walls, and crystalisation of the rock matrix in the holes in the structure.


Thumbnail of image below (this version only 63kb) – if you would like you to do so, you can download the full 543 megapixel version from the following link and zoom in to see the detail (I recommend right clicking on link below and selecting “save as”):

http://www.thornett.net/Large_files_RAG_Wordpress/Microscopy_C_torquia_261117/C_torqia_composite_100_ images_PNGwithalpha261117.png

Microscopy S annectans Finis Shale Texas x4 objective Zeiss IM microscope 26/11/2017

Damian popped around and together we looked at a slide of fossilised coral from the USA.

Stereocorypha is a form of extinct coral. The slide here is from Jack County, Texas. Photographs were taken on my Zeiss IM microscope with x4 objective, using the Bresser Mikrocam 9.0 camera and Diagnostic Instruments adapter and ZU clamp, with Zeiss 910137 dual observation adapter (originally designed for a teaching microscope but bought into use here to allow both the binocular head and ZU clamp to be simultaneously used on the IM microscope).

The following slides show:

  • Three images of the same field of view to demonstrate the (limited) effect on this slide of using a single polarization filter. The filter used is one made by Zeiss.
  • A composite of 49 pictures combined using Microsoft’s Image Composite Editor.

Andy & Damian

Bresser Mikrocam 9.0 installed on Zeiss IM microscope:

The photos in the composite were taken using a blue filter. The set of three were the only ones using polarising filter – in this case one made by Zeiss. This is single linear polarisation NOT cross-polarisation:


A set of three images to demonstrate effect of polarisation on the same field of view:

Without polarising filter:

Polarising filter position I:

Polarising filter position II:

Composite of 49 images taken using blue filter (non-polarised):

This file is so large I have had to ZIP file into a compressed folder. The picture within it is a 70% quality JPEG version of the composite – the only way I could get such a large photo onto WordPress!

S annectans Finis Shale Texas x4 obj Zeiss IM 261117 (stitched x49 photos)JPEG-70percent-cropped



Microscopy of microfossils and rock formations from Scarborough

These slides were purchased from SDFossils on ebay Sept 2017.

They compose of a five slide set of thin sections – one is of shelly limestone showing fossils. The others show rock structure – including oolites which look for all the world like fossils but aren’t!

All photos on Zeiss IM microscope with Bresser MikrOkular camera. For this post only x4 and x20 objectives were used.


Shelly Limestone

Shelly Limestone x4 objective – microfossils are seen within the stone

For comparison purposes the following photo is from the Museum of Wales, showing fossils within limestone:


Oolite or oölite (egg stone) is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. The name derives from the Ancient Greek word ??? for egg. Strictly, oolites consist of ooids of diameter 0.25–2 mm; rocks composed of ooids larger than 2 mm are called pisolites. The term oolith can refer to oolite or individual ooids. Some exemplar oolitic limestone, a common term for an oolite, was formed in England during the Jurassic period, and forms the Cotswold Hills, the Isle of Portland, with its famous Portland Stone, and part of the North Yorkshire Moors. A particular type, Bath Stone, gives the buildings of the World Heritage City of Bath their distinctive appearance (Wikipedia).

x4 objective:

Laminated sandstone & mudstone

The following are photographs of microscopy of two laminated rock sections (sandstone and mudstone) from Scarborough.

In geology, lamination is a small scale sequence of fine layers (so called laminae) that occurs in sedimentary rocks. Laminations are normally smaller and less pronounced than bedding. Lamination is often regarded as planar structures one centimetre or less in thickness, whereas bedding layers are greater than one centimetre. However, structures from several millimetres to many centimetres have been described as laminae. A single sedimentary rock can have both laminae and beds. Lamination consists of small differences in the type of sediment that occur throughout the rock. They are caused by cyclic changes in the supply of sediment. These changes can occur in grain size, clay percentage, microfossil content, organic material content or mineral content and often result in pronounced differences in colour between the laminae. Weathering can make the differences even more clear. Lamination can occur as parallel structures (parallel lamination) or in different sets that make an angle with each other (cross-lamination). It can occur in many different types of sedimentary rock, from coarse sandstone to fine shales, mudstones or in evaporites. Lamination is a fine structure and hence it is easily destroyed by bioturbation (the activity of burrowing organisms) shortly after deposition. Lamination therefore survives better under anoxic circumstances, or when the sedimentation rate was high and the sediment was buried before bioturbation could occur. Lamination develops in fine grained sediment when fine grained particles settle, which can only happen in quiet water. Examples of sedimentary environments are deep marine (at the seafloor) or lacustrine (at the bottom of a lake), or mudflats, where the tide creates cyclic differences in sediment supply. Laminations formed in glaciolacustrine environments (in glacier lakes) are a special case. They are called varves. Quaternary varves are used in stratigraphy and palaeoclimatology to reconstruct climate changes during the last few hundred thousand years. Lamination in sandstone is often formed in a coastal environment, where wave energy causes a separation between grains of different sizes (Wikipedia).

Laminated sandstone x4 objective:

Laminated sandstone x20 objective:

Laminated mudstone x4 objective:

Microscopy of fossilised Ostracod-filled Elimia tenera thin section

Ostracod-filled Elimia tenera from Laney MBr. Green River Shale Eocene Sweetwater County, Wyoming, purchased from SDFossils from ebay Sept 2017.

Andrew Thornett

Elimia tenera, formerly known as Goniobasis tenera, is an extinct species of freshwater gastropods (snail) with an operculum, in the aquatic gastropod mollusk family (Wikipedia).

Picture of these fossilised snails (Elimia tenera):

Ostracods, or ostracodes, are a class of the Crustacea, sometimes known as seed shrimp. Some 70,000 species have been identified, grouped into several orders (Wikipedia).

Picture of modern Ostracod:

I like this fossil thin section as it contains fossils within fossils which can be seen in the microscopy photos below.

My photos of Ostracod-filled Elimia tenera through Zeiss IM microscope (Bresser MikrOkular camera):

x4 objective:

x20 objective:

Microscopy of fossilised Squalicorax pristodontus tooth

Thin section of tooth of Squalicorax pristodontus from Cretaceous Phosphate beds Ouled Abdoun Basin Moroccao purchased from SDFossils on ebay Sept 2017.

Andrew Thornett

Pictures of teeth from this shark and what palaeontologists think the shark looked like:

My photographs of my thin section of Squalicorax pristodontus tooth today under Zeiss IM microscope (Bresser MikrOkular camera):

The question I was keen to answer was whether this were easily seen differences between this tooth and my previous project (microscopy of O. Vinc tooth – posted earlier today). My conclusion was that, although similar structures could be seen in both teeth, the ratios of tooth in the different layers was significantly different and the enamel appears to be thinner. I wonder if that impression is real?

x4 objective:

x32 objective:





Microscopy of thin section of fossilised extinct Odontospis vincenti shark tooth

Microscopy of thin fossil section purchased from SDFossils, UK-based company based on ebay, Sept 2017:

By Andrew Thornett

Odontaspis vincenti tooth.

This specimen came from the Eocene age phosphate mines of Morocco.

From Wikipedia: Odontaspis is a genus of sand shark with two extant species.Odontaspis species can reach a length of about 3.6 metres (12 ft). Currently living versions (extant species) are large-bodied sharks with long, conical snouts, broad-based dorsal and anal fins, and an asymmetrical caudal fin with a strong lower lobe. Their teeth are large, with prominent narrow cusps.They are distinguished from the similar genus Carcharias by the absence of crushing posterior teeth.These bottom dwelling, deepwater sharks can be found in temperate and tropical waters of all the oceans.
Wikipedia also lists three extinct species: Odontaspis aculeatus Capetta & Case, 1975, Odontaspis speyeri (Dartevelle & Casier, 1943), Odontaspis winkleri Leriche, 1905. Wikipedia does not list Odontaspis vincenti – however the Museum National D’Histoire Naturelle registers on its website three exogenous rock specimens from this species, and a number of fossil suppliers are marketing teeth from this species – I guess this might be due to the large Moroccan find from which my sample comes.
The fossil thin section provided me today with the opportunity to compare the structure of the fossilised tooth with that of teeth from currently living sharks. In practice, obtaining microscope images from Google from sharks turned out to be very difficult (I couldn’t find any!) so I present below some photos from other living animals.

My images of O vincenti fossilised tooth thin section with Zeiss IM microscope today (Bresser MikrOkular camera):

x4 objective:

x20 objective:

x32 objective:

Pictures of O vincenti fossilised tooth:

Pictures of modern teeth histology:


Comparing above to one of my photos (x4) of the fossilised tooth:

The above picture is analogous to the first diagram above it showing pulp, odontoblasts, dentin, enamel – demonstrating that fossilised teeth show similar structure at microscopic levels to modern teeth.


Ostracod filled Elimia tenera microfossil thin section under the microscope

A new type of microscope slide arrived whilst I was away – a selection of three thin sections of microscopic fossils in rock.

This first one is Ostracod filled Elimia tenera, Laney Mbr. Green River Shale, Ecocene, Sweetwater County, Wyoming.



Naked eye image:


As you can see, the fossils are visible by eye without magnification.

From Wikipedia:

Ostracods, or ostracodes, are a class of the Crustacea, sometimes known as seed shrimp. Some 70,000 species have been identified, grouped into several orders. Wikipedia

Scientific name: Ostracoda
Class: Ostracoda; Latreille, 1802
Kingdom: Animalia
Phylum: Arthropoda
Rank: Class
Higher classification: Crustacean
Lower classifications: Podocopida, Myodocopina, Halocypridina

The following image of a modern Ostracod comes from Wikipedia:

Elimia tenera, formerly known as Goniobasis tenera, is an extinct species of freshwater snail with an operculum, in the aquatic gastropod mollusc family Pleuroceridae (Wikipedia).

Pictures of this snail can be found at http://rsquirespaleo.blogspot.co.uk/2016/08/elimia-tenera-commonly-misidentified.html

So, the shells of the snail were then filled with Ostracods – I assume after the former died – and the whole lot became fossilized.


LOMO MNC-1 polarising microscope images. Each caption lists the intermediate magnifying lens used – there is also a low power objective (I think 2x) and the magnification provided by the Bresser MikrOkular camera).

Ostracod-filled-Elimia-tenera-Wyoming-LOMO-Pol-microscope-0-6x-intermed-lens-260817-panorama-10-images.jpg (below – cross polarising filters – interestingly the crystals that form the fossilised snail shell (Elimia) appear to have different mineral content (appear pink/orange in image below) than those that form the fossilised Ostracod (blue) – I don’t know why that should be or which mineral these colours represent):

Ostracod-filled-Elimia-tenera-Wyoming-LOMO-Pol-microscope-2x-intermed-lens-260817.bmp (below):

Ostracod-filled-Elimia-tenera-Wyoming-LOMO-Pol-microscope-4x-intermed-lens-260817.bmp (below):

Ostracod-filled-Elimia-tenera-Wyoming-LOMO-Pol-microscope-7x-intermed-lens-showing-details-of–Elimia-shell-260817.bmp (below – also shows some birefringence in crystals making up matrix of rock around fossils – you can see here that the rock is composed of small crystals consistent with layers being laid down at bottom of ancient lake or sea):

Ostracod-filled-Elimia-tenera-Wyoming-LOMO-Pol-microscope-7x-intermed-lens-showing-whole-Ostracod-260817.bmp (below):


To obtain a higher power image, I changed over to the Zeiss Photomicroscope III for the next image, a panorama of 5 photos at 10x magnification (with Bresser MikrOkular camera):

Ostracod-x10-mag-Planapo-objective-Zeiss-Photomicroscope-III-260817-Panorama-5-photos.jpg (below):

I am quite impressed by the detail visible in the image!