Expeditions on LSG Lab

What is an ammonite ? Part 1

Sun, 08 Jun 2025 00:00:00 +0000

With this text, I start a series of 5 articles on the fossils of the extinct subclass Ammonoidea, belonging to the class of cephalopods. Ammonoids, or ammonites, are obviously not “sea snails”, even though their shell form resembles that of Gastropods : like all cephalopods, ammonites are thought to have a head with 2 camera-type eyes ¹ and several tentacles ; they were nectonic organisms swimming in open water, not crawling on the seafloor. The first ammonites appeared nearly 400 million years ago in the Devonian. Ammonites were widespread in seas and oceans for about 334 million years before becoming completely extinct 66 million years ago. Ammonites are of great importance in paleontological research : they are some of the most abundant fossils, especially in Mesozoic rocks. Their spiral shells are common in many rocks, for example the limestones and marls of the Jura mountains (Jurassic-Cretaceous), where we also find calcitic plates called Aptychi, which are elements of ammonoid lower jaws.

Albian (Lower Cretaceous) ammonites from the Jura mountains.

Quenstedtoceras flexicostatum. ammonite. Lower Oxfordian (Upper Jurassic), Vaud, Switzerland. Image from the gallery

Laevaptychus sp., ammonite lower jaw element (Aspidoceratidae indet.). Lower Oxfordian (Upper Jurassic), Vaud, Switzerland. Image from the gallery

The term «ammonite» was already employed in ancient times. It is linked to the Ancient Egyptian god Amun, who was often represented with ram horns that indeed look like ammonites.

Ammonite Cantabrigites aff. cantabrigense. Albien (Crétacé inférieur), Jura. Image from the gallery

For a long time, there was no scientific description for the formation of fossils. They were rarely linked to ancient life, and more often thought to appear spontaneously in rocks. The first to identify ammonites as extinct cephalopods was Robert Hooke (1635-1703). Hooke compared the ammonites he had found with Nautilus, a modern cephalopod with a spiral shell.

Extant Nautilidae use their shell to maintain neutral buoyancy at different depths. The inner whorls of their shells are divided into hollow sections, called hydrostatic chambers. The end of the shell (living chamber) is undivided because it contained the soft body, and ends with an aperture. The chambered part is called phragmocone. Hydrostatic chambers contained a mix of air and water. A tube, called siphon or siphuncle, runs through every chamber ; its function is to modify their air/water content. Removing water from the hydrostatic chambers made the shell lighter that the surrouding water and allowed move upwards while pumping air out and adding water made the mollusc sink downwards.

Extant Nautilus pompilius Image source.

Cut of the shell of an extant Nautilus Image source.

R. Hooke observed the same features in ammonite fossils. They also had a shell divided into chambers, although the wall between them is much more complex than in extant Nautilus. The last whorls, where preserved, are free of chambers. And in some specimens, even the siphuncle is preserved. Robert Hooke didn’t know its function, however he observed it on some of his fossils.

Dorsoplanites dorsoplanus. ammonite. Moscow, Upper Jurassic, around 149 years old. Note the siphon on the right picture. Image from the gallery

The discovery of the nature of ammonites and other fossils made Robert Hooke formulate several hypotheses. He argued that organic substances were replaced by mineral substances from the surrounding environment, which lead to the formation of fossils. He also noted that most fossils were marine, but they were found at places very far from the sea and above the sea level; he concluded that seas existed there a long time ago, but disappeared because of structural changes in the earth’s crust. Lastly, he proved that some fossils belonged to extinct groups, and supposed that living organisms could change in the course of an evolution.

One of Robert Hooke’s illustrations of ammonites (1).

Ammonite fossils are useful in geology. Their well-developed classification and their rapid evolution allow to use them as time markers to date sedimentary rocks. Observing the migrations of various ammonite species also yield information on marine paleogeography, like the existence of openings or currents.

Source: Mironenko, A.A., 2015: Wrinkle layer and supracephalic attachment area: implications for ammonoid paleobiology. Bulletin of Geosciences 90(2): 389–416.

The image above is a reconstruction of ammonites. It is based on modern scientific data about ammonoid anatomy, including soft body anatomy. I will discuss the accuracy of different reconstructions in another article.

The elongated tube below the head is the hyponome, also named funnel or siphon (not to be confused with the siphuncle). It is a locomotory organ common to all cephalopods. Cephalopods eject water from the mantle cavity through the hyponome, creating a reactive force that pushes the mollusc in the opposite direction.

Image source.

It is thought that propulsion was the main mean of active movement of ammonites, and allowed them to swim moderately fast. However, some species could also swim by moving their tentacles. Lastly, some ammonoids were not adapted to active swimming, and were carried by water currents.

From the point of view of evolution, ammonites are closer to Coleoidea than to Nautiloidea. It can seem unlikely, considering that I just said that it is precisely the comparison with nautilids that allowed to identify ammonoids as cephalopods. It turns out the evolution of Coleoidea and Ammonoidea was divergent: while ammonites kept and perfected their outer shell, the shell in coleoids first became internal, then it lost its importance, causing at first the disappearance of the phragmocone (as in calmars) and then the complete loss of the shell in octopuses. Nautilids, on the other hand, kept a spiral external shell as well. Caracters common to ammonites and nautilids are either inherited from primitive common ancestors or as s result of convergent evolution. The origin of ammonoids, as well as their relation to extant coleoids, will be discussed in the next publication.

Belemnite fossil (Cephalopoda; Coleoidea), Jurassic. The phragmocone (gray part) is located inside the soft body.

Don’t miss : Paleobiology and evolution of Ammonoidea . Part 2

Bibliography

Hooke R., Discourse on Earthquakes. The posthumous works of Robert Hooke. 1705. p. 279-289.
Ogura A., Yoshida M., Moritaki T., Okuda Y., Sese J., Shimizu K.K., Sousounis S., Tsonis P. A., 2013 : Loss of the six3/6 controlling pathways might have resulted in pinhole-eye evolution in Nautilus. // Scientific Reports. 2013. Vol. 3. art. 1432.

Extant Coleoidea have well-developed eyes, comparable to the human eye, but with accommodation regulated by horizontal movement of the crystalline lens. Nautilids have very simple eyes without cornea or crystalline lens that don’t allow a good vision. Genetic studies show that the eyes of Nautilus were simplified in the course of evolution, while primitive cephalopods had eyes comparable to those of Coleoidea (2). Therefor it is thought thought that ammonoids had a good vision, especially considering that they inhabited shallow well-lit epipelagic zones and that many of them were active predators. ↩︎

The conservation of a paleontological collection

Sat, 07 Dec 2024 00:00:00 +0000

I’ve been a fossil collector for nearly 10 years. My collection has been very useful to acquire a certain practical knowledge of paleontology and to transmit it to others. I started by displaying on a shelf the few fossils I had in the beginning, which was convenient to show my collection to all my guests. Now, I haven’t got any space for shelves. On one hand, the apartment in Geneva is quite small, on the other hand, my lab takes a lot of space. I leave fossils in boxes with labels. To show my fossils, I organize temporary exhibitions. The first of them took place on the 25 May 2024. Sometimes fossil collectors find fossils of a great scientific value. These fossils should be donated to museums, where they can be studied or exposed (immediately or after some time). Some of my fossils are now housed in the Timiryazev biological museum in Moscow. But scientific value disappears if locality and stratigraphy data is lost. The topic discussed here is of interest for any amateur paleontologist : how to store a fossil collection and the data that goes with it ? The methods used here also apply to mineral collection, with only some changes in geological data.

My fossil collection in Moscow, 2019

My paleontological exhibition in Geneva, 2024

Field notes

It is difficult for beginners to understand the importance of field notes. Why not keeping everything in the catalog (see below) ? Indeed, you could theoretically collect some fossils, come back from the expedition and fill a page with the location, date and level for each fossil. But in practice this turns out to be just impossible : preparation and cataloging take time, fossils collected in the same location but not in the same time or in the same layers tend to happily mix in the routine lab mess. Especially in expeditions that last several days, good field notes are always required. In case an expedition doesn’t yield fossils, field notes can also be very useful. These expeditions won’t leave any trace in the catalog, but the information that some beds don’t contain fossil might be precious for further searches.

If this seems familiar, then you won’t de able to sort the fossils from the last expedition for several months.

The most difficult is to choose what to include in your notes. Clearly not the weather or where the eggs you ate came from ! It is the information related to the specimens that is the most valuable: precise location, date, stratigraphy, searched levels and collecting techniques (surface or in situ collecting, sifting…). Fossils must be grouped by level and the level must be written on the package when possible. Information about the state of the outcrop can be added to the notes.

It is essential to keep the field notes. The materials used must be water and light resistant. Scanning your notes and keeping them on a computer is a good idea: notebooks get lost sometimes.

Don’t write with water-soluble markers…

The catalog

The catalog is a list that describes the whole collection. It links each specimen with a unique number. Each page of my catalog contains the number of a separate specimen, the scientific name, location, date of find, preparation techniques¹, stratigraphic position and classification². A photo of each specimen is also inserted. To take high-quality photos, especially if you want to share them with researchers, I really recommend to buy a camera with a specialized macro lens (or maybe you have an expensive phone that takes acceptable photos). In terms of flexibility, nothing compares to modern interchangeable lens digital cameras.

A page from the LSG Lab 2024 catalog :

| № 1011 |

Name: Craspedites subditus
Locality: Fili park, 2nd ravine
Date of collecting: 22.02.2022
Collected by Max Fomin

Preparation	Restoration
mechanical	acrylic primer and Paraloid B-72 consolidation

Stratigraphy

Chronostratigraphy	Lithostratigraphy	Biostratigraphy
Erathem: Mesozoic	Bed: lower sea urchin lens	Zone: Garniericeras catenulatum
System: Jurassic
Serie: Upper
Stage: Volgian
Substage: Upper

Classification
Kingdom: Animalia
Phyllum: Mollusca
Class: Cephalopoda
Subclass: Ammonoidea
Order: Ammonitida
Superfamily: Perisphinctoidea
Family: Dorsoplanitidae
Subfamily: Craspeditinae

Olympus OM-D E-M5 II mirorless digital camera with an Olympus 60 mm f/2.8 macro lens. This equipment was used to make almost every photo in fossil collection

There are many significant advantages in making a digital catalog. Is is easier to redact, send by e-mail or insert photos. Additionally, it gets lost less often! This is supported by experience, a lot of specimens donated to my mineralogy association had numbers on them, but the owner had lost his notebook with the lists. My own first catalog (paper) was lost when I was still in Moscow, while the electronic version survived moving to another country and still exists today! It was very handy to have it when I had to choose which specimens I was taking with me by the way. In any cases, you should make one or preferably more spare copies of the catalog.

The catalog number is stuck on the fossil itself. To attach it, permanent but reversible methods are required. Forget paper glue (label coming off), scotch (very rapid degradation of both glue and plastic), regular pens (soluble in virtually everything and degrades under light), permanent marker directly on the fossil (not reversible). Use archival grade products. If number are lost, does all the work with the catalog make sense?

Old numbers (right) are held by paper glue. They will be replaced soon. A new number (on the left) is coated with Paraloid B-72, which does not degrade with time. Archival grade ink was used to write down the number.

Collection storage

The sections before were about how to keep the information about a fossil collection. Here I continue by detailing how to store the specimens themselves. Once prepared and numbered, fossils must be stored somewhere. Every fossil cannot be on display, because that would take too much space. Most fossils are kept in boxes, one for each fossil, but sometimes similar small non-fragile fossils are put in the same box. Boxes start to be unpractical as the collection grows. The best solutions are flat drawers, which allow easy access to the whole collection. But if those aren’t available, standardized boxes or zipbags are also a good choice (example) ³. I`m not that organized myself yet, I have to admit… Or best of the best (for small fossils), little metal boxes with a glass lid, such as watch parts containers. They can be found used in large lots if you are lucky. When fossils are stored in drawers, it is essential keep the specimens from moving when the drawer is opened/closed, as friction can damage the fossil’s surface. You can put a piece of foam, or tissue (paper is not a good idea as it degrades and produces acid, which will damage most fossils).

External physical conditions (temperature, humidity…) can greatly influence the state of fossils. Pyritic fossils are the most unstable, but no fossil likes overly humid air. Stabilizing fossils after preparation, and storing them in a place with the least aggressive environment available will allow to avoid degradation without being in a clear room.

It’s now obvious that organizing a collection takes a lot of time. It is worth to make an effort to keep it in the best condition, so it could last tens or even hundreds of years. I hope that this article was helpful for finding the appropriate techniques for fossil conservation

Useful links

Paleontological research tips I: field notes for amateurs and professionals alike (The Coastal Paleontologist)

Archival marking & labelling in fossil collections (Zoic Palaeotech)

This part might turn out to be very useful if a specimen needs additional preparation in the future, or to exclude any interference with scientific results. ↩︎
The same form of course can be applied to mineralogical collections. Only the geological data to be included will be a bit different, and systematics won’t be used (a mineral classification can be added instead). ↩︎
These boxes have to be stored in a drawer, not under direct sunlight. UV rays will degrade plastic and possibly the fossils inside. ↩︎

Cretolamna – the marine reptile-eating shark and its 50 million years history

Fri, 18 Oct 2024 00:00:00 +0000

The genus Cretolamna is remarkable in the evolutionary history of lamnoid sharks. This genus appeared approximately 100 million years ago and became extinct 50 million years ago, surviving the end-Cretaceous mass extinction. It is the direct ancestor of the genus Otodus, which comprehends the largest known marine predators, including the well-known megalodon, a 20 m shark. Cretolamna may have been preying on plesiosaurs and mosasaurs, themselves fearsome predators more than 7 m long…

Cretolamna appendiculata. tooth. Upper Cretaceous, around 90 million years old.

Glickman (Glickman, 1958b) described the genus Cretolamna for fossil teeth of Lamna appendiculata that became the type species. Teeth of Cretolamna were previously assigned to modern salmon sharks Lamna for somewhat similar teeth between these two genera. This similarity is however linked to convergence, as both forms have similar ecological niches. Glickman’s data proves that there cannot be any close genetic link between Cretolamna and Lamna : the teeth of the species C. appendiculata, 80 millions years older, have nevertheless a broader tooth crown, and therefor a better developed cutting function allowing to prey on larger animals. A regression towards narrower crowns is impossible, as it would be very unfavorable to the species. Teeth of Lamna situated at the posterior-most edge of the jaw are highly reduced, and will probably completely disappear with evolution, meanwhile no reduction is observed in the posterior teeth of Cretolamna. These observations show that the dentition of Cretolamna has already followed a long evolution to adapt to its ecological niche, while Lamna is a recent genus.

Cretolamna appendiculata. tooth. Upper Cretaceous, around 90 million years old.

There are two spellings of this genus - CretOlamna and CretAlamna. The second one is a typographical error that appeared in Glickman’s article published in 1958. Glickman stated it was an error and continued to use the spelling Cretolamna, as most paleontologists at that time. However, other researchers later insisted on the spelling Cretalamna, which is now used as frequently as the first one.

During its existence, Cretolamna had a global distribution. Cretolamna appears in the Cretaceous around 100 million years ago. Teeth found in Cretaceous sediments are usually of medium size (around 20 mm), and only rarely exceed 25 mm. Tooth morphology indicates an ecological niche similar to that of extant Lamna for most species. Cretolamna were active predators preying mostly on fish, as well as on cephalopods. Broader teeth are larger and characterize species that attacked very large animals. It was thought for a long time that C. appendiculata was the most widespread species during the Cretaceous, and that it existed for 50 millions years. However, a study (Siversson et al., 2013) shows that the evolution of Cretolamna was much more complicated. species with a cutting dentition, specialized in hunting large prey, evolved several times from smaller, less specialized forms. Siversson et al. Described 6 new species of Cretolamna that existed between 98 and 82 million years ago (Upper Cretaceous).

Very broad Cretolamna tooth. Upper Cretaceous, around 90 million years old.

The skeleton of a 7 m long plesiosaur ¹ , Futabasaurus suzukii, found in Japan had 5 Cretolamna teeth stuck in its bones, and 82 other Cretolamna teeth were found during the extraction of the skeleton. Several shark had eaten the plesiosaur carcass and lost some of their teeth (Shimada et al., 2010). Shimada et al. Assign this case to scavenging, but some aspects indicate that it is more likely to be a shark attack. The scavenging version doesn’t explain why so many teeth were found next to the skeleton. Teeth of sharks specialized in scavenging, Hexanchidae and Crassonotidae, are commonly found next to marine reptile skeletons (i. e. Paparella et al. 2017, Serafini et al. 2020). There is always a lot less teeth that what was found next to Futabasaurus suzukii, meanwhile Cretolamna teeth are much better attached to the jaw than in the simplified dentition of Hexanchidae. On the other hand, during the attack of a large living reptile, the loss of a great number of teeth is very likely. Shimada et al. explain the high number of teeth by hypothesizing that scavenging occurred multiple times, but in this case it is difficult to explain why all the teeth belong to one species, considering that Cretolamna was not a scavenger but an active predator (which obviously doesn’t exclude occasional scavenging). The sense of smell in lamnoids being not best developed among sharks (see Glickman, 1980), sharks like Hexanchidae, specialized in scavenging and having a better sense of smell, must have been advantaged. The version that Cretolamna attacked a living but vulnerable plesiosaur is one of the likely possibilities.

Hexanchus shark tooth. Upper Cretaceous, around 90 million years old.

At the end of the Cretaceous period, plesiosaurs became extinct, and their niche was filled with another group of reptiles - mosasaurs. Cases of lamnoid sharks scavenging on mosasaurs are known (Everhart, 2004). Cases of lamnoid sharks attacking mosasaurs are also documented (Rothschild et al., 2005), and those are undoubtedly attempts to kill living animals. As they were not fatal, mosasaur bones present traces of subsequent bone growth (healing) and infection. Mosasaurs were probably preys of Cretolamna (C. sarcoportheta, C. borealis). Cretolamna teeth became larger and broader at the end of the Cretaceous.

While some sharks became extinct at the end of the Cretaceous, Cretolamna was not affected by the Cretaceous-Paleogene extinction (65 million years ago), and survived until 50-46 million years ago. Paleogene forms include large predators as well as less specialized species.

Cretolamna is the ancestor of all Cenozoic otodontids : genera Otodus, «giant» sharks like Otodus megalodon, and Palaeocarcharodon, sharks with blade-like serrated teeth, descend from Cretolamna. The origin of otodontids Parotodus and Megalolamna is still not very clear, they descend either from Cretolamna, either from primitive Otodus. The concurrence with more evolved otodontids is thought to be the main cause of Cretolamna’s extinction.

Otodus minor shark tooth. Paleocene, around 60 million years old.

Otodus obliquus. shark tooth. Eocene, around 50 million years old.

References

Glickman L. S., 1958b. On the rates of evolution of lamnoid sharks [in Russian]. Doklady AN SSSR, 123(3) : pp. 568-571.
Glickman L. S., 1980. Evolution of Cretaceous and Cenozoic lamnoid sharks [in Russian]. Ed. Nauka.
Paparella I., Maxwell E. E., Cipriani A., Roncacè S., Caldwell M. W., 2017. The first ophthalmosaurid ichthyosaur from the Upper Jurassic of the Umbrian–Marchean Apennines (Marche, Central Italy). Geol. Mag., 154(4) : pp. 837-858.
Rothschild B. M., Martin L. D. and Schulp A. S., 2005. Sharks eating mosasaurs, dead or alive? Netherlands Journal of Geosciences, 84(3) : pp. 335-340.
Serafini G., Amalfitano J., Cobianchi M., Fornaciari B., Maxwell E.E., Papazzoni C.A., Roghi G. & Giusberti L., 2020. Evidence of opportunistic feeding between ichthyosaurs and the oldest occurrence of the hexanchid shark Notidanodon from the Upper Jurassic of Northern Italy. Riv. It. Paleontol. Strat., 126(3) : pp. 629-655.
Shimada K., 2007. Skeletal and dental anatomy of Lamniform shark, Cretalamna appendiculata, from Upper Cretaceous Niobrara chalk of Kansas. Journal of Vertebrate Paleontology, 27(3) : pp. 584-602.
Shimada K., Tsuihiji T., Sato T. and Hasegawa Y., 2010. A remarkable case of a shark-bitten Elasmosaurid plesiosaur. Journal of Vertebrate Paleontology 30(2) : pp. 592–597.
Siversson M., Lindgren, J., Newbrey, M.G., Cederström, P., and Cook, T.D. 2015. Cenomanian–Campanian (Late Cretaceous) mid-palaeolatitude sharks of Cretalamna appendiculata type. Acta Palaeontologica Polonica, 60(2): pp. 339–384.

Useful links

Cretolamna on gallery.lsglab.org.

Otodontidae on gallery.lsglab.org.

The plesiosaur could be even larger - up to 9.2 m. ↩︎

The Jurassic of the Fili Park

Sun, 29 Sep 2024 00:00:00 +0000

Fili is a large park in Moscow, located on the right bank of the Moskva river. Among paleontologists in Moscow, Fili is known for decades for its very fragile fossils of the latest Jurassic, that is between 147 and 140 million years old. It took one hour to get to get from my home to Fili, which made it one of the most accessible fossiliferous locations for me. I often visited Fili with friends from my paleontology club. I walked from the underground station to the upper part of the park, with some houses, walking paths and playgrounds. Then I had to take some stairs to go down the abrupt slope and arrive on the bank.

Image source

Two creeks are visible from the quay. These creeks cut through Jurassic clay. The clay is black with a bluish tint and very different from usual soil. Fossiliferous strata are divided in three zones characterized by ammonite species (from oldest to youngest) : Epivirgatites nikitini, Kashpurites fulgens and Garniericeras catenulatum. The zone under nikitini, Virgatites virgatus, was only accessible on the Moskva bank before the quay was built.

First creek.

Second creek

Ammonites are one of the most common fossils here. They are exceptionally well-preserved: the pristine shell still subsists ¹. But unfortunately they are also very fragile: the inside of the shell is filled with clay or weak phosphorite, or even empty. The only way to to keep an ammonite is to take it inside its surrounding matrix and consolidate it with glue before preparation. Despite this approach, few entire ammonites can be saved ².

All three zones deliver ammonites, but it is in fulgens and catenulatum that the best specimens are found. We need to dig clay with a big shovel until we see an ammonite sticking out. Then a piece of matrix around the ammonite is taken out and packed with plastic film or aluminium foil (newspaper is not suitable as it won’t hold the specimen, without what it will fall apart). Brachiopod and bivalve inner moulds, as well as a lot of well-preserved belemnites, are also found.

Craspedites subditus. ammonite. Scale bar = 1 cm

In fact, digging in Fili is much harder than one could imagine. The clay is very wet and flows everywhere. In my dig that exposed the catenulatum zone, we even had a little stream flowing right out of the wall. We had to dig a gutter to make a way out for the water and the mud. But clay, instead of flowing through, was constantly blocking the gutter, so we had to dig it again every ten minutes or so. It was also important to see the ammonites at the right time, as they could disappear forever in a mud flow from above.

And of course these creeks are full of mosquitoes. The problem is that, when you are digging, you can’t scratch yourself or kill mosquitoes. Once I was getting out an ammonite, and my back was all bitten by mosquitoes. When I got that ammonite out and packed it, I scratched my back against a tree. What a relief!

Vertebrates are also found there. An ichthyosaur skeleton with a complete skull was even found, but it disappeared in a private collection despite the will of a specialist to study it. But isolated teeth and vertebrae of sharks, bony fishes, plesiosaurs and ichthyosaurs are much less unique. Most of them are found in the nikitini zone, although fulgens contains the same fossils. They are found in a condensed lens using a sieve (these are very small fossils, ranging from several millimeters to 1 or 2 cm). This condensed lens is located at the level of water, and therefore it is constantly flooded. Big holes are dug to extract material from the condensed lens, and so water and mud flows to the bottom of the hole.

Apart from teeth, sea urchin spines (they indicate the right layer), gastropods and (unfortunately very fragile) bivalves and brachiopods can also be found.

Once I got out of my hole, with a large Fiskars shovel in one hand and a sieve filled with mud in the other, and started washing the sediment through the sieve. A little girl was walking in the park with her father when she saw me, and asked him: “Dad, what is the guy doing?”. And her father said with a very confident voice: “He’s gold panning” ³.

Sphenodus stschurovskii. shark tooth. Fili park, Jurassic

Synechodus sp. shark tooth. Fili park, Jurassic

How did people react when they saw some paleontologists in the park? Most people didn’t even notice me. Some came to ask some questions about what I search and what we find here. When I was coming back home, exhausted because I had dug the whole day, with a heavy backpack because of all the equipment and finds, I may have seemed strange to some people in the underground because I carried a large shovel and had mud traces on my face.

Fossils from Fili in my collection

Thanks to the preservation of ammonites from the Moscow area, Alexander Mironenko, a well-known specialist of ammonite anatomy, could make a lot of discoveries about their soft-body organization. ↩︎
Which doesn’t mean we should only focus on whole specimens. Sometimes fragments have more scientific value. ↩︎
People usually confuse me with a gold panner because I use a sieve to search small fossils like shark teeth. Gold panners don’t use sieves but pans, so rocks and sands are washed away and gold, much denser that everything else, stays on the bottom. A sieve would be useless here, as it will let the small gold flakes through. But many people don’t see this difference and just remember that in films, gold panners shake some round things in water. ↩︎

Paleontological exposition on the 25 May 2024, Geneva

Sun, 26 May 2024 00:00:00 +0000

This was the first exhibition of my collection; up to now all the specimens were kept in boxes in my room (and until 2022 in Moscow I had a room where I exposed some fossils). My dad once told me that I could get a room for one day to organize an exposition. Therefor, I started to prepare the specimens and the lecture that I was going to read on the exposition.

Some specimens from my collection exposed in Moscow, 2019.

I already started to prepare the exposition in early March. In march, I already chose the specimens I wanted to expose and wrote the text for my presentation, in which I only made some correction in May. However, many things that had nothing to do with the exposition actually disturbed me and took most of my time. The exposition took place on the 25 May. As I understand now, I should have started preparation even earlier, so I could focus on organization the last weeks before the exposition, and some last-moment organizations problems could have been avoided. As an example of such a problem, I put number 9 instead of 11 as the address on the exposition affiche, and noticed it when it was already sent. If I had enough time, I could have read it 10 times before sending.

I told about the exposition to many acquaintances, and also asked a teacher from my school to send the affiche of the exposition to the whole school, which he did.

I exposed fossils from Russia as well as recent specimens from France and Switzerland: shark teeth (from the Carboniferous, Jurassic, Cretaceous and Neogene), Mesozoic marine reptiles’ bones, Jurassic and Cretaceous ammonites, bivalves, gastropods, brachiopods, bryozoans and some other fossils. They were disposed in vitrines that I borrowed at the SGAM. Some specimens had descriptions and images. Everyone knows what sharks are, but few people know about brachiopods and bryozoans.

I disposed the specimens in 2 vitrines.

I actually should have prepared more vitrines to make the specimens and labels more visible.

Ichthyosaur forelimb

Bryozoans (early Carboniferous) and their description.

The presentation was divided into 5 parts:

Introduction part. What is paleontology. How fossils are preserved.
Geological history of Switzerland. This part was about ancient seas and oceans in Switzerland : the Tethys ocean and the North Alpine foreland basin.
About expeditions, how and where to search fossils.
Scientific significance of fossils. I discussed muscle imprints on ammonite fossil shells, shark evolution, biostratigraphy, determination of ancient environmental conditions using fossils.
Some addresses of geological and paleontological clubs in Switzerland, and some paleontological websites.

I should have added a part about fossil preparation, but this will be for another time.

Roughly 15 persons came for the presentation. It looked like everyone found it interesting, there were some questions. And there was around 20-25 people on the exposition. Three people from my school came as well, and one of them was very impressed to see shark teeth that are 330 million years old. I must say that the exposition went well, and it is always good for the specimens to get out of their boxes.

Biography of L. S. Glickman (1929-2000)

Fri, 26 Apr 2024 00:00:00 +0000

Leonid Sergeyevich Glickman was a paleontologist specialist of shark evolution. His studies made a revolution in the classification of elasmobranchs. He developed new research methods based on dental morphology, which led to remarkable advancements in the study of shark evolution.

Leonid Glickman was born on the 23rd January 1929 in Leningrad. His father was a well-known chemist – Serguei Abramovitch Glickman. In 1939, Glickman and his parents moved to Kiev. His mother died just before the war. In 1941, Leonid Glickman and his father were evacuated in Tashkent. At the end of the war, they moved to Saratov, where his father was appointed chief of the colloidal chemistry department of the Saratov State University. At the age of 18, L. S. Glickman graduated from school and entered at the biology and soils department of the SSU.

The Saratov region is well-known for its upper cretaceous deposits delivering a rich elasmobranch fauna. By the end of school, Leonid Glickman already collects shark teeth. During his studies at the SSU he gathers a collection of several tens of thousands of vertebrate fossils from the Saratov cretaceous : sharks (teeth), chimaeras (teeth and bones), bony fishes (teeth, bones and scales), ichtyosaurs (vertebrae), plesiosaurs (teeth and bones), and a jaw fragment and a partial skeleton of pterosaurs [1].

L. S. Glickman gets in touch with L. I. Hozatskiy, paleontologist, specialist of turtles at the Leningrad State University. In 1950, Glickman moves to Leningrad, and L. I. Hozatskiy helps for his transition to the LSU. Leonid Glickman graduates from University in 1952, with a paper called «The Upper Cretaceous Marine Vertebrates from the Volga bank near Saratov», which will be the basis of his first scientific paper [1].

L. S. Glickman wants to continue his research on elasmobranch evolution. But the beginning of the 50s is the peak of stalinian antisemitism, and despite his brilliant studies, finding a job with the name Glickman turned out to be hard and he is hired in 1952 only as a secretary of the A. P. Karpinskiy Geological Museum, where he also works as a guide. In 1953, he takes part in two expeditions where he collects fossil shark teeth. Then, in 1954, on the request of the Geological Institute of the SSU, Glickman works on upper cretaceous sharks (Glickman, 1954) and collects teeth from the Saratov and neighboring regions. In 1954, Glickman obtains a scientific post at the A. P. Karpinskiy Museum. At the same time, he starts to prepare his candidate* thesis. During this period of his life, he publishes numerous papers about sharks evolution. On the 25 December 1958, he defends his thesis «On the classification of sharks» with success and obtains the degree of candidate in biology. This thesis will be the base of his monograph «Paleogene sharks and their stratigraphic value» [5], a revolution in the classification and the study of sharks. In 1964, he also publishes the «Elasmobranchii» section in the «Fundamentals of Paleontology», a reference guide for soviet paleontologists [6].

L. S. Glickman with the skull of an extant Carcharhinus , 1960-s

L. S. Glickman actively collects fossil shark teeth material. He studies the stratigraphy of cretaceous and cenozoic deposits of Moscow region, Volga, Kazakhstan, central Asia, and collects detailed shark teeth material from different horizons. Most of his expeditions were not funded, but paid by Glickman himself, and in 1960, during one of his expeditions, he even lost his salary for a month, because his direction considered that he was not at work.

L. S. Glickman during an expedition in Kasakhstan, 1960-s.

In 1970, Leonid Glickman moves to Vladivostok, where he will work 10 years in the Marine Biology Institute. Here, he wanted to study modern sharks, but he doesn’t really have this opportunity. He actually studies salmonids and gives consultations to other researchers in evolutionary biology. Glickman also prepares his doctor thesis «The evolutionary patterns of cretaceous and cenozoic lamnoid sharks». He attempts to obtain the degree of doctor in geology in 1972 at the geological department of the Moscow State University. This attempt wasn’t successful, and he makes another one in 1974 at the Institute of Paleontology in Moscow. This time, he tries to obtain the degree of doctor in biology. This try also fails, and one of the judges, V. V. Menner, recommends to make some improvements in the thesis. In 1976, Glickman tries for the last time to defend his thesis at the Marine Biology Institute, with the support of V. V. Menner. However, the same year, Glickman takes part in an expedition in Kamchatka for 6 months, and the defense doesn’t take place. In 1980, his doctor thesis will be published under the name «Evolution of cretaceous and cenozoic lamnoid sharks» [7].

At the end of the 70s, L. S. Glickman disagrees more and more with his direction at the Marine Biology Institute. He leaves Vladivostok and comes back to Leningrad. At the same time, his collection is transferred to the Darwin Museum in Moscow, where it is currently kept. Being very poor, Glickman has to work as a security agent in a fabric, and he had a hip fracture that wasn’t looked after. However he still publishes papers about sharks (Glickman and Zhelezko, 1985, Glickman and Dolganov, 1988a, 1988b, Glickman and Averianov, 1998 and other).

In 1999, Glickman takes part in his last expedition in Kazakhstan. He dies a bit later, on the 31 January 2000, at the age of 71.

* Candidate - a title attributed for a thesis to researchers in USSR and Russia. The title “doctor” is similar to candidate and is attributed for a second thesis

Research

Since the very beginning of his studies, Glickman chooses the evolution of elasmobranchs as his specialization. He seeks to develop new research methods. He gathers a great quantity of fossil shark teeth and studies extant shark remains kept in museums. The study of this material allowed to draw important conclusions about the systematics and the evolution of sharks.

Glickman gathered a collection estimated at around 200 000 specimens [4] of fossil shark teeth from the eastern Europe and central Asia, collected by Glickman himself or by other scientists, and also shark teeth collected from the floor of the Indian and Pacific oceans on the research stations «Vitiaz», «Ob» and «Lomonosov». He also incorporated the collections of A. S. Rogovitch, I. F. Sinzov and other scientists, saved from the liquidation of the A. P. Karpinskiy Geological Museum. The collection is kept in the Darwin Museum in Moscow.

L. S. Glickman with his collection of fossil shark teeth, 1950-s.

In 1970-1980, Glickman studied the salmonids and made some hypotheses on their evolution.

Leonid Glickman published 4 monographs (Glickman, 1964a, 1964b, 1980, Glickman et al., 1987) and 33 scientific papers. Glickman’s main concept is his elasmobranch classification. He noticed some fundamental differences in the organization of the neurocranium [7], the jaws and the dentition [5] of lamnoid sharks and other elasmobranchs. Additionally, the teeth of lamnoid sharks are made of osteodentin (a bone-like dentin tissue), while other sharks have a layer of ortodentin under the enameloid, and a pulpar channel (Fig. 1). These observations made Glickman separate the lamnoid sharks from other extant sharks and rays, and state their affinity with extinct osteodont-toothed elasmobranchs. Based on dental histology, he divided elasmobranchs in two infraclasss : Ortodonts and Osteodonts [5]. This division is confirmed by the similarity of cranial anatomy of Carcharhini (see part “Classification of sharks after Glickman, 1964a”) and Xenacanths (freshwater paleozoic sharks that Glickman supposed to be the ancestors of Carcharhini), and the similar organization of the neurocranium of Chlamydoselachus[7].

Classification of sharks after Glickman, 1964a :

Subclass Еlasmobranchii

Infraclass Orthodonta
- Superorder Cladoselachii
  - Order Cladoselachida
    - Fam. Сladoselachidae
    - Fam. Denaeidae
  - Order Сladodontida
    - Fam. Сladodontidae
    - Fam. Symmoriidae
    - Fam. Tamiobatidae
- Superorder Xenacanthi
  - Order Xenacanthida
    - Fam. Xenacanthidae
- Superorder Polyacrodonti
  - Order Polyacrodontida
    - Fam. Polyacrodontidae
- Superorder Chlamydoselachii
  - Order Chlamydoselachida
    - Fam. Chlamydoselachidae
- Superorder Carcharini
  - Order Hexanchida
    - Suborder Hexanchoidei
      - Fam. Hexanchidae
    - Suborder Heterodontoidei
      - Fam. Heterodontidae
  - Order Squatinida
    - Suborder Echinorhinoidei
      - Fam. Echinorhinidae
    - Suborder Squaloidei
      - Fam. Squalidae
      - Fam. Dalatiidae
      - Fam. Cetorhinidae
    - Suborder Squatinoidei
      - Fam. Squatinidae
    - Suborder Ginglymostomatoidei
      - Fam. Ginglymostomatidae
    - Suborder Pristiophoroidei
      - Fam. Pristiophoridae
    - Suborder Rajoidei
      - Superfam. Rhinobatoidea
        
        Fam. Rhinobatidae
        
        Fam. Asterodermatidae
        
        Fam. Platyrhinidae
      - Superfam. Pristioidea
        
        Fam. Pristidae
        
        Fam. Torpedinidae
      - Superfam. Rajoidea
        
        Fam. Rajidae
      - Superfam. Myliobatoidea
        
        Fam. Myliobatidae
        
        Fam. Trygonidae
        
        Fam. Hypolophidae
  - Order Carcharhinida
    - Fam. Palaeospinacidae
    - Fam. Scyliorhinidae
    - Fam. Triakidae
    - Fam. Carcharhinidae
    - Fam. Sphyrnidae
Infraclass Osteodonta
- Superorder Ctenacanthi
  - Order Ctenacanthida
    - Fam. Ctenacanthidae
  - Order Tristychiida
    - Fam. Tristychiidae
- Superorder Hybodonti
  - Order Hybodontida
    - Fam. Hybodontidae
    - Fam. Ptychodontidae
- Superorder Lamnae
  - Order Orthacodontida
    - Fam. Orthacodontidae
  - Order Odontaspidida (=Lamniformes Berg excl. Orectolobidae)
    - Superfam. Odontaspidoidea
      - Fam. Odontaspididae
      - Fam. Jaekelotodontidae
      - Fam. Otodontidae
      - Fam. Carcharodontidae
      - Fam. Cretoxyrhinidae
      - Fam. Alopiidae
      - Superfam. Isuroidea
        
        Fam. Isuridae
        
        Fam. Lamiostomatidae
      - Superfam. Scapanorhynchidea
        
        Fam. Scapanorhynchidae
        
        Fam. Mitsukurinidae
      - Superfam. Anacoracoidea
        
        Fam. Anacoracidae

Fig. 1 : Elasmobranch teeth histology. A – Osteodont tooth. B – Ortodont tooth. En – enameloid, ost – osteodentin, ort – ortodentin, p – pulp. After Glickman, 1964a.

L. S. Glickman developed a scientific method for the study of shark evolution based on teeth. Shark teeth are abundant in Phanerozoic rocks starting from the Devonian. Descriptions of genera and species made on the basis of arbitrary sets of characters, which are widespread in paleontology and were so until recently in biology, turned out to be artificial for sharks, which closely resemble to each other. Many sharks that share a large number of characters are not united by phylogenetic links, but have a similar ecological niche instead. The study of extinct sharks turned out to be even more difficult. Attempts to describe generic and specific characters of ancient sharks are made since a long time, but the overwhelming quantity of characters present on shark teeth, and the difficulty to determine the phylogenetic relationships between extinct and extant sharks were the biggest problems of paleontologists. As demonstrated by Glickman, the proportions of the shark’s tooth crown is linked with its feeding behavior, and consequently with its lifestyle. Shark teeth can be subdivided into four groups: clutching (ударно-хватательные in Glickman, 1964a), grasping (колющие), cutting or tearing (режущие, рвущие), and crushing (дробящие). Clutching teeth are conical, elongated relatively to their width, and thick. They characterize sharks adapted to various preys and different habitats (for example Lamna). Grasping teeth are elongated and thin. They are attributed to coastal sharks that feed on small fish and cephalopods (example - Odontaspis). Cutting teeth are wide and thin, while tearing teeth have thick crowns. Such teeth allow to cut or tear flesh, and belong to superpredators (examples are Isurus, Carcharodon, Squalicorax). Crushing teeth are flat or conical but shorter than clutching teeth. They characterize sharks living close to the seafloor and eating molluscs (bivalves as well as cephalopods), small fish, crustaceans(examples are Squatina and Heterodontus). The tooth shape is connected with many other features (such as the shape and disposition of fins), as it has a strong influence on the shark’s lifestyle. In the course of evolution, sharks tend to adapt to new ecological niches, which leads to changes in feeding behavior, so the crown geometry changes to adapt to new functions. Later sharks specialize and ameliorate their tooth functionality (the crown elongates or widens more and more), in the same time secondary adaptation occur, which are linked to tooth overload, lack of space in the jaw and so on (widespread phenomenons : appearance of a lobe on the labial side at the crown-root junction to prevent crown break, atrophy of posterior teeth due to the enlargement of anteriors and laterals). The study of shark teeth is made more difficult by heterodonty – the function of upper and lower, anterior and lateral teeth can be different, and in some cases teeth of different jaw position change at different rates during evolution. The method proposed by L. S. Glickman consists in determining the feeding behavior of extinct sharks based on functional types of teeth, and studying secondary adaptation to these tooth functions. It is possible to reconstruct the phylogenetic relationships between extinct shark species, genera and families by studying shark teeth of different age, on the basis of regularities in crown geometry changes during evolution, and secondary adaptation [see 3, 5, 7].

The study of sharks with the method proposed by Glickman demonstrated their high evolution rates. L. S. Glickman started to develop the use of shark teeth in biostratigraphy, which was continued by R. A. Schwajeaite, V. I. Zhelezko and other paleontologists.

References

Glickman L. S., 1953: Верхнемеловые позвоночные окрестностей Саратова. Предварительные данные. [Upper cretaceous vertebrates from the Saratov region. Preliminary data, in Russian] // Учёные записки СГУ, 38:51-54.
Glickman L. S., 1957b: О генетической связи семейств Lamnidae и Odontaspidae и новых родах верхнемеловых ламнид [On the genetic link of the families Lamnidae and Odontaspidae and new genera of upper cretaceous lamnids, in Russian] // Труды геол. музея им. А. П. Карпинского, 1:110-117.
Glickman L. S., 1958b: О тэмпах эволюции ламноидных акул. [On the rate of evolution of lamnoid sharks, in Russian] // Доклады АН СССР, 123(3):568-571.
Glickman L. S., 1959: Направление эволюционного развития и экология некоторых групп меловых эласмобранхий. [The direction of evolutionary development and the ecology of some groups of cretaceous elasmobranchs, in Russian] // Труды 2й сессии Всесоюзного палеонтологического общества 226-234.
Glickman L. S., 1964a: Акулы палеогена и их стратиграфическое значение. [Paleogene sharks and their stratigraphic value, in Russian]. Наука.
Glickman L. S., 1964b: Подкласс Elasmobranchii. Акуловые. [subclass Elasmobranchii. Sharks, in Russian]. Основы палеонтологии том 11: Бесчелюстные и рыбы 196-237, Наука.
Glickman L. S., 1980: Эволюция меловых и кайнозойских ламноидных акул. [The evolution of cretaceous and cenozoic lamnoid sharks, in Russian]. Наука.
Popov, E. V., 2016: An annotated bibliography of the soviet palaeoichtyologist Leonid Glickman (1929–2000) // Proceedings of the Zoological Institute RAS, 320(1):25–49.
Popov E. V. and Glickman E. L., 2016: The life and scientific heritage of Leonid Sergeyevich Glickman (1929-2000) [in Russian]. Proceedings of the Zoological Institute RAS, 320(1):4-24.