The Narwhal´s lesser Tusk

I have seen a whole lot of narwhal tusks in museums, many skulls of narwhals (Monodon monoceros), some fully mounted narwhal skeletons and even several specimens with  double tusks. But so far I have never ever seen the vestigal right tusk of a narwhal somewhere on exhibit. Male narwhals have always two tusks, but in general, only the left one is noticable and protrudes out of the upper lip. The right tusks however usually remains embedded within the maxillary bone and normally never erupts. This tiny tusks are much smaller than the erupted tusks, and you can only see them if they are extracted out of the skull, or if the bone of a skull is already damaged. So far the very only vestigal narwhal tusk I had seen was one which was still embedded into a the broken bone of a skull I have seen at the archive of the Zoological Museum at Copenhagen. But much of it was still hidden under bone.

So I was really highly astonished when I recently discovered such a specimen which was fully bare of bone. But it was not in a Zoological museum, but in the exhibtion of the Landesmuseum Württemberg at Stuttgart, a historical museum about archeology and the history of the territory of Württemberg. It includes a historic cabinet of art and curiosities, the Kunstkammer („art chamber“), which dates back to the late 16th century. The tusk is a loan from the Natural History Museum at Stuttgart, probably as some sort of surrogate for a big narwhal tusk, which would not have fitted into the showcase. It was also only labeled as „narwhal tusk“, without any additional information about its unusual nature, but the old-fashioned hand-written labels indicates that it is  not of modern origin.

Vestigal right narwhal tusk, Kunstkammer Landesmuseum Württemberg, Stuttgart

As you can see, the shape differs a lot from those of the iconic „unicorn“ tusks. It fully lacks the spiraling, which is so typical for the erupted tusks. But this one still seems to have some parallel grooves. It is also not fully straight, because it is not twisted. The erupted tusks are often not completely straight, but form a more or less pronounced corkskrew-shape. But they always follow a nearly perfect straight line around their centre, as the spiraling of the tusks prevents them from growing in a curve.

The tip is also very thin and not pointed. If the big tusks erupt, they are also very pointed at first, but abrade their tips over time. At the next photo you can also see a detail in which it differes from the big tusks. Its foramen apicale, the apical opening of the tooth which connects the pulp with the blood vessels and nerves of the surrounding bone, is only very small. In the big tusks it is fully open, and about the diameter of the whole tooth. This is the area where dentine and cementum are produced and where the tusks continuously grows. The pulp gets its nutrution over the blood vessels which enter the foramen apicale, and here is also the interaction of the sensory nerves with the tusk. But the small vestigal tusks don´t need to grow anymore, nor do they need much nutrition or have any more sensory function, so the apical formanen is nearly closed.

Foramen apicale of a vestigal right narwhal tusk, Kunstkammer Landesmuseum Württemberg, Stuttgart

You can also see that it has a very clean colour, unlike the yellowish erupted tusks, that have often dark veined spiral grooves. This colour comes from algae, diatoms and various particles from the surrounding water and sediments, which can stain the narwhal tusks like coffee does on human teeth.

The unerupted right tusks are also quite variable in shape, as they have nearly no more selection pressure. That is similar to human wisdom teeth, which also show a massive amount of variation, and which can be also vestigal with reduced sizes or aberant shapes of the crowns and roots.

Here is also a photo which shows the tusk in the showcase, together with a number of toadstones (fossil teeth of Lepidotes), a fossil oyster from the Swabian Alps, an ammonite and a large fossil shark tooth:

Vestigal right tusk of a Narwhal, Kunstkammer Landesmuseum Württemberg, Stuttgart

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A new model of Meyerasaurus – or how to bodypaint a plesiosaur

Today I wanted to show you some photos of a life-sized model of Meyerasaurus, a rhomaleosaurid from the Toracian stage of the early Jurassic, whose fossils were found at Holzmaden. The model was made by my friends from kamyk.pl, a Polish company which specialized in the creation of zoological and paleontological models for museums. I had already the chance to take a close look at some of their wonderful models at the last two fossils fairs at Leinfelden-Echterdingen, the largest anual fossil fair of Europe. One of their latest models – the Meyerasaurus – was made for the Natural History Museum at Lodz, Poland.

Meyerasaurus by kamyk.pl, Natural History Museum Lodz. Photo by Piotr Menducki

Here is another photo of the model:

Meyerasaurus by kamyk.pl, Natural History Museum Lodz. Photo by Piotr Menducki

When the model was already finished and awaiting its paintjob, Piotr Menducki of kamyk.pl asked me for some proposals about possible colour schemes and pattern. So I reflected about possible and probable colours and patterns which could fit with this model. I wanted to avoid too much influence from other models and life reconstructions of plesiosaurs. The reconstructions from the BBC-series „Walking with Dinosaurs“(1999) and „Sea Monsters“ (2003) for example have been highly influential, and even today you can see a whole lot of reconstructions which are clearly based on their designs. So instead of looking at other models and paleoart, I focused on modern marine animals to get some ideas.

Meyerasaurus model by kamyk.pl, photo by Piotr Menducki

There is sometimes a certain tendecy to depict mesozoic marine reptiles with quite fancy colours and patterns similar to terrestrial reptiles. But if you look at modern marine animals, it´s quite noticeable that their main range of colours and patterns is still comparably overseeable. Small and medium sized animals have much more often striking patterns and flashy colours, whereas bigger animals tend to have more uniformous colours and lesser or even absent patterns. Of course this is no rule, more some sort of tendency, with a whole lot of exceptions (like whale sharks or oarfish). But you can see that tendency even within the ontogeny of many animals, particularly in fishes and reptiles. Young komodo dragons, nile crocodiles and tiger sharks – to name just some iconic and well-known species – have very prominent patterns during their youth, which fade more and more when they grow bigger, until they have nearly fully vanished in big old specimens.

So I looked at various sharks, big marine fish, cetaceans, seals and marine reptiles to find certain patterns which we can find in all of those lineages. I started with the leatherback turtle, one of the most amazing reptiles of our time, and in many respects the closest living thing to a plesiosaur. Adult leatherback turtles are usually of a dark mottled grey main colour, with small brighter spots and a brighter area in the area of their throats. It´s notable that younger leatherbacks have also often much more contrast-rich skin with much bigger white skin areas than adult specimens.

Leatherback sea turtle (Dermochelys coriacea), photo from Wikipedia

This combination of different shades of grey, combined with white and black patterns, is very common among a whole lot of highly different marine animals, from mammals, to birds, certain reptiles, sharks, rays and teleost fishes. So it seems really not too far-stretched to assume that many mesozoic marine reptiles were likely somewhere within this range as well. Given the enormous number of known plesiosaurs (plus countless still unknown species) which lived for an incredibly long time in the oceans of the world, we could probably bet that they had not only a lot of variation in colours and patterns, but also that at least some were really within the most common colour schemes of modern marine animals of comparable size.

The combination of mottled grey as a main colour, combined with brighter areas at the ventral parts of the body and some lighter or darker spots seemed to be a good and reasonable concept.

If you look at mammals, you can also find species which resemble the pattern and colours of the leatherback, for example the infamous leopard seal (Hydrurga leptonyx).

Leopard seal (Hydrurga leptonyx), photo from Wikipedia

Another photo of a leapard seal, which shows the head in detail:

It´s really interesting how there are not only many different shades of grey, ranging from silvery-white to dark grey, but also bright and dark spots as well. Many other seals have very similar coats, for example harbour seals or grey seals, and to a lesser degree also mediterranean monk seals.

Among cetaceans, the Atlantic spotted dolphin (Stenella frontalis) fits also quite well herein, but there are also many other cetaceans with lesser pronounced spots which have a quite non-uniformous mottled grey skin. Another interesting, and rarely seen example would be subadult narwhales, which are still much darker than adults. It is also quite important to keep in mind that many cetaceans have a surprisingly high intraspecific variation of colours and patterns, depending on age and sex.

It is also quite important to keep in mind that the very common idea that aquatic animals show countershading with darker dorsal and lighter ventral areas is also not a universal rule, but also more a tendency. Many seals and cetaceans are for example nearly fully dark, like sea-lions or false killer whales, whereas some like the super-bizarre strap-toothed whale Mesopodon layardii show even some negative countershading whith large whiteish dorsal areas. In many cases you see also only small white ventral areas, for example around the mouth of throat, or sometimes also in the pelvic area, like in sperm whales or Southern right whales.

Here is also a photo of a salmon shark (Lamna ditropis), which I show here for obvious reasons:

Admittedly, that´s not a very common pattern for pelagic sharks, which are in general without distinct spots, except for markings on the fin tips. That reminds me also on a story I experienced some years ago. I was at late evening in a rockabilly bar, when I accidentally heard a conversation of an older and already somewhat drunk punk with another guy. I have no idea what their conversational topic was, but one sentence sticked in my mind:

„The great white shark isn´t white at all, it looks more like an old filthy car.“

That´s really the coolest description of Carcharodon charcharias I´ve ever heard, and there is really something to it.

Another example of a cartilaginous fish with dark main greyish colour and bright spots, even one from tropical areas, the spotted eagle ray  (Aetobatus narinari):

And just for the case that the leopard seals, the salmon sharks or the narwhales give you still somehow the impression that this fits better into colder areas, take a look at this wonderful ocean sunfish (Mola mola):

Ocean sunfish (Mola mola), photo from Wikipedia

It is also noteworthy that some comparable colour schemes can be even found among some marine snakes.

Of course it is still fully speculative to give a plesiosaur some variation of the shown patterns and colours, and perhaps some of them were really much more colourful in life. But on the other hand it is perhaps still more likely than some fully speculative fancy colours and patterns which we see in no or only extremely few modern marine animals. In any case, the team of kamyk.pl did a really good job when they painted their Meyerasaurus.

Here is also a photo of the original fossil, exhibited at the Museum am Löwentor, Stuttgart:

Veröffentlicht unter Evolution, Fische, Haie und andere Knorpelfische, Paläontologie, Skulpturen, Wale | Hinterlasse einen Kommentar

A King of Cods

Today I want to show you a „Dorschkönig“ or „king of cods“ from the collection of the Zoological Museum Kiel:

„King of cods“  was the Name given by fishermen to Atlantic cods (Gabus morhua) with a rare cranial malformation of the head which results into a pug-face-like shape. This specimen was caught in the waters of Eckernförde in 1869 and was part of the ichthyological collection of zoologist Karl August Möbius.

This kind of malformation is not just found in cods but also known from many other fish species. You can see another example of a small king of cod specimen here. In salmonids this can be for example the result of an infection with Myxobolus cerebralis, a myxosporean parasite which can affect the skeletal development in young fish. But there are of course also other factors which can lead to cranial deformations, so it is often quite hard, if not impossible, to trace back the original cause.

Veröffentlicht unter Bild des Tages, Fische, Teratologie | Hinterlasse einen Kommentar

The bearded Leviathan – not your everyday Basilosaurus

Basilosaurus – the great mammalian leviathan of the Eocene – was beyond doubt one of the most spectacular creatures which ever swam the oceans of the world.  But despite the fact that fossils of this ancient cetacean have been known since well more than one and a half centuries, many aspects of its anatomy and biology still remain enigmatic. I´ve written in an older blog article why archaeocetes were surely not the skull-headed and shrink-wrapped pseudo-reptiles as which they are usually depicted. They had surely much more soft-tissue around their skulls and necks than most people think, and also nearly certainly possessed  well-visible and functional vibrissae (see here why). Dominic Grabowski recently created this truely wonderful life-depiction of a chunky Basilosaurus with volumous upper lips, and countless fine vibrissae on its chin and upper lips.

Basilosaurus by Dominic Grabowski

I think this is really one of the most life-like depictions of an archaeocete I have ever seen, and despite its unconventional appearance, it really doesn´t look wrong. Dominic managed to blend the features of a whale with those of a hippo in a really good way. If you take a close look, you can even see fine isolated hairs covered the rest of the body. This is of course fully speculative, but plausible. We just have no idea how and when exactly whales lost their fur. With few exceptions like walruses and to a lesser extreme degree elephant seals as well, modern seals have all a fairly well developed coat. So were those derived but still partially amphibious protocetids like Maiacetus still fully covered by fur as well?

Well, we´ll just never know. But those animals mainly lived in comparably warm subtropical or even tropical areas, and I could well imagine that they lost most of their coat at a quite early stage – similar to modern hippos and the even more terrestrial pygmy hippos. And it´s really interesting to keep in mind that they didn´t just lost their whole fur, but just highly reduced it, similar to other „bald“ mammals (including humans). Hippos and even manatees and dugongs have fine isolated hairs all around their bodies. It could be possible that they have some tactile function, similar to the more specialized vibrissae in the facial area, and it seems not unplausible that such hairs could have been still present in animals like Basilosaurus.

 

Veröffentlicht unter Paläontologie, Populäre Irrtümer, Säugetiere, Wale | Hinterlasse einen Kommentar

Why maned lionesses are not that special (and why they don´t baffle scientists)

Perhaps you have heard about the recent report about a lioness at Oklahoma City Zoo, which „mysteriously“ grew a mane. As usual „scientists are baffled“, at least according to the news-site which spreads the story.  However, the whole case is neither mysterious nor that unusual. The lioness at Oklahoma Zoo, her name is Bridget, is already 18 years old, what´s quite old for a lion, far older than they usually they live in the wild. Even big cats age, and like humans, they also can have a menopause, and as a consequence thereof, a change in the production of sexual hormones. We all have male and female hormones in our bodies, which are in a quite complex interaction with our metabolism. Changes of the hormone levels can result into a lot of physical changes, from increased or decreased muscle growth, accumulation or breakdown of body fat or the reduction or reinforcement of secondary sexual characteristics like body hair.

In lions, the growth of manes is controlled by testosterone (similar to the growth of beards in humans), so changes in the level of this hormone can result into an increase or decrease of mane growth (the whole thing is of course even much more complex, and also depends on the subspecies of the lion). And it doesn´t matter if it is a male lion of a female lion. A male lion with very low testosterone levels will hardly grow a mane, whereas a female lion with high levels of testosterone can grow a small mane. The origin of such an inbalance can be quite variable. It can be a congenital defect, a dysfunction of hormone producing organs or a hormone-producing tumor for example. It can be (more likely in males than females) a result of an accidental or artifical removal of the gonads. Something like that is likely if a comparably young lion shows for example a mane which is atypical for its sex. But if a lion, which has been totally normal for its whole life, starts to exhibits unusual mane growth at old age, it is highly likely a result of the hormone imbalance after the menopause. The production of typical sexual hormones decreases, and the effects of the normally suppressed antagonistic hormones can become more visible.

I have seen such cases myself. There were two lion-sisters at Stuttgart Zoo, Schiela and Elektra (both 1994-2008), which grew both a well visible mane at old age. Here is a photo of one of them, which I took in 2003:

Maned lioness at Wilhelma Zoo, Stuttgart 2003

As you can see, the mane resembles those of a young male lion which just hits puberty. It´s neither as long, nor as extensive or dark as those of a typical male lion. It is more the feline equvialent of the facial hair seen in some (often more elderly) women.

Lioness with mane, Wilhelma Zoo, Stuttgart, 2003

It was sadly not that easy to take photos of her, but you can see some better ones here, here and here.

Schiela and Elektra were also not the only other known case of old lionesses with manes, and there is really nothing about them that would baffle scientists.

Lioness with mane, Wilhelma Zoo, Stuttgart, 2003

 

Veröffentlicht unter Populäre Irrtümer, Säugetiere, Teratologie | Hinterlasse einen Kommentar

Photo of the Day: Chiemsee Pike

Pikes have always been among my favourite native European freshwater fishes. Their taxonomy has  become much more complex in recent years, when two additional European species were described, so that Esox lucius is no more the only of its kind in Europe. This particular topic will (hopefully) anytime be featured in a more extensive blogpost about the amazing diversity of pikes.

Last year was a particularly good one for me in terms of finding pikes in the wild. Besides some really impressive specimens I saw during my trip to Königssee and three small ones I discovered in a lake at the Swabian Alps, I could also take some underwater photos of several young pikes at Chiemsee. This one is likely the best, which shows a pike of around 15-20 cm:

Northern Pike, Lake Chiemsee

You can see very well how the camouflage pattern of the pike blends within the structure of the underwater vegetation.

Veröffentlicht unter Bild des Tages, Fische | Hinterlasse einen Kommentar

The Art of Xylotheques – Wooden Books about Woods

Xylotheques are quite likely the most artistic and beautiful examples of herbaries. Dating back to the early 18th century, they were still to some degree made in the tradition of the old cabinets of curiosities, which combined all fields of nature with arts and crafts. They were dedicated to educate about the characters and traits of the various trees and shrubs of a certain area.

In contrast to a simple casebound herbary, which usually only includes preserved leaves and other pressed parts of a plant, the „books“ of a xylotheque also includes the massive wood and often many more parts of a tree. Every book is made from the wood of one kind of tree or shrub, with the spine of the book covered with bark, and sometimes even specific lichens.

The insides can include dried branches and leaves, seeds, cones, little wooden containers with pollen and standardized cubes of wood to show its  specific weight. There can be also cross-sections of branches, dried roots and charcoal.

The backbone of the book has also a removable panel at the inside, with a piece of paper with a written description of the tree and the content of the book.

There were never many xylotheques, and they have been always quite worthy, as it was quite expensive to make them. This examples are from the xylotheque exhibited at the University of Hohenheim, which includes a large number of wooden books from two different series.

This smaller books are lesser complex in construction and also include not as much inventory:

 

 

 

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The Tarbosaurs of Warsaw

Last year I made a city holiday at Warsaw and took the opportunity to visit a lot of museums there. I was especially eager to see the Museum of Evolution, which is located in the monumental Palace of Culture and Science. One of the exhibition rooms has a whole gang of Tarbosaurs on display, including some famous specimens. Tarbosaurus gets much lesser attention than Tyrannosaurus, so I thought this would be a good chance to post some photos of the skeletons at Warsaw.

That´s likely the most famous one:

The information table next the the left skeleton is around 1,8 m in height, so this specimen was only a subadult with a hip height of not much over 2 m in life, with a total length of somewhat over 4 m or so.

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Tarbosaurus and Tyrannosaurus seem really quite similar at first look, but if you look at the proportions of their skulls, you can see that the one of T-rex was significiantly more massive and especially also much broader.

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A photo which shows how the specimens was excavated:

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There is also a cast of a complete skeleton of a pretty big specimen, which easily dwarves the other skeletons nearby.

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It was not easy to get them all completely on a photo, but it gives you an idea about the massive size difference.

There was also a cast of another skull and some isolated bones as well:

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And last but not least some old paleoart:

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Photo of the Day: Sri Lankan Spotted Chevrotain

Today´s photo fo the day features one of the smallest extant artiodactyls, the tiny Sri Lankan Spotted Chevrotain (Moschiola meminna) from the South Asia animal section of Haus der Natur, Salzburg:

Sri Lankan Spotted Chevrotain (Moschiola meminna), Haus der Natur, Salzburg

Veröffentlicht unter Bild des Tages, Säugetiere | Hinterlasse einen Kommentar

Curiosity of the Day: Whale bone chairs

Today´s curiosity of the day are chairs made of whale bones. The first one is constructed of two large cervical vertebrae and apparantly pieces of ribs for the chair legs. It is exhibited in the Zoological Museum at Copenhagen, Denmark.

Whale bone chair, Zoological Museum Copenhagen

I have no idea how comfortable this chair was to sit on, but I really like the nearly gigeresque Design which would surely fit very well into a Science Fiction movie, for example for a Predator spaceship.

Here is another example of a different construction, made from the bones of a fin whale. It was exhibited at the Staatliches Museum für Naturkunde Karlsruhe (State Museum of Natural History Karlsruhe) but is now sadly no more on display.

Whale bone chair, State Museum of Natural History Karlsruhe

 

Veröffentlicht unter Anatomie, Curiosity of the Day, Wale | Hinterlasse einen Kommentar