The Nightmare Look of Naked Owls – how Feathers Conceal a Bird´s True Shape

Today I want to show you one of the coolest bird specimens I have ever seen in a museum, a bodycast of a barn owl (Tyto alba) with removed feathers. This gives us a great opportunity to see the enormous amount of volume which is made up by the feathers of a bird. It shows also very well how much the external appearance of an owl differs from the actual body below.

Bodycast of a barn owl with removed feathers, Museum Mensch und Natur, Freiburg. Photo by Marku Bühler

This is of course a particularly extreme example as owls have especially voluminous feathers on their heads and necks, what makes the difference even more remarkable.We are often used to think that feathers and fur are only thin coats that closely follow the underlying body shapes.

Bodycast of a barn owl with removed feathers, Museum Mensch und Natur, Freiburg. Photo by Marku Bühler

But in many cases we see a massive difference between the apparent body proportions with feathers or fur and the real body proportions below.The barn owl here is an excellent example for this.

Bodycast of a barn owl with removed feathers, Museum Mensch und Natur, Freiburg. Photo by Marku Bühler

It was on exhibit in a special exhibition of the Museum Mensch und Natur (museum of man and nature) in Freiburg which I visited a few years ago. I don’t think the featherless body was a real plastinated owl but quite likely a cast. We can see here all the features which are usually hidden below the thick plumage, including the weird skin folds around the ears of the owl.

Bodycast of a barn owl with removed feathers, Museum Mensch und Natur, Freiburg. Photo by Marku Bühler

Besides the featherless body was also a full taxidermy specimen for a better visualization of the differences.

Barn owl taxidermy specimen, Museum Mensch und Natur, Freiburg. Photo by Marku Bühler

A particularly good idea was also the jar filled with the removed feathers to show just how much volume they have.

Bodycast of a barn owl with removed feathers, Museum Mensch und Natur, Freiburg. Photo by Marku Bühler

Of course it’s somewhat more than the volume of the feathers as long as they are still attached to the skin. Something we also often tend to forget is the weight of feathers. They are symbols of weightlessness, and singular feathers have very little weight indeed. But altogether they summarize to a considerable weight which can make up a lot of a bird’s total weight. Reconstructions of extinct birds and of course certain lineages of feathered theropods as well (and yes, of course I am are aware that birds are technically theropod dinosaurs, yet I find it still useful to discriminate between anatomically modern birds and feathered mesozoic theropods for several reasons). We have to keep the volume in mind when we reconstruct the outlines of such animals from their bare bones, especially on body areas like the necks. The differences in the appearances can be really dramatic as even a moderate amount of feather volume can change the body shape a lot. The weight of plumage is also a considerable factor when it comes to weight estimates for extinct birds and feathered theropods as well, especially for those capable of flight which had well developed wing feathers. In the Haast´s eagle (Hiraaetus moorei) for example, the feathers of a specimen of 12,33 kg weighed around 0,85 kg alone.

Veröffentlicht unter Anatomie, Vögel | Schreib einen Kommentar

Berardius, the bus-sized deep sea predator with barnacle covered battle teeth

There is an enormous marine carnivore which grows as long as a bus, and most people are fully unaware of its very existence. Nearly everyone knows sperm whales, but if you would ask people about the world’s next largest extant predator (if we exclude baleen whales which are still carnivorous and sometimes surprisingly predatory), it’s very likely that a lot of people would struggle. Many would likely answer that orcas are the second largest carnivores, but this formidable predators are still not at the second range after sperm whales. In fact they aren’t even at the third range. I am sure that a lot of people would be very surprised to learn that there are besides sperm whales other predatory marine mammals larger than orcas in the world’s oceans. But hardly anyone could name them, and even those who know them are often not fully aware of their enormous size.

Baird´s beaked whale (Berardius bairdii) by Markus Bühler

The name of this beast is Baird’s beaked whale (Berardius bairdii), sometimes also called the giant beaked whale. This little known leviathan is an inhabitant of the northern pacific ocean, whereas its slightly smaller antarctic sister species, the Arnoux‘ beaked whale (Berardius arnuxii), inhabits the circumpolar oceans of the southern hemisphere. Giant animals gain usually a lot of attention, even more so if they are predatory. Even children’s books are full of sperm whales, baleen whales, orcas, whale sharks or basking sharks and you can see them in countless documentaries. So how could it be that Berardius somehow evaded to get attention? Beaked whales are in general quite elusive and still among the least known big mammals of the world.

Even today some species are only known from a handful of specimens and we still know nearly nothing about much of their behavior. As late as 2019 a „new“ species of Berardius was described from Japanese waters, Berardius minimus (more about earlier implications for this new species at Lord Geekington). It had been known to Japanese whalers since a long time and was called kuro-tsuchi (meaning „black Baird´s beaked whale). In contrast to B. bairdii which is greyish with some white markings in the chest area, B. minimus is nearly fully jet-black. It also differs in its body proportions from Berardius bairdii, which occurs in the same area. B. minimus has also a stouter melon, a shorter and more compact body shape and a much smaller size, growing „only“ to about 6,9 meters. It also seems to suffer more from cookie cutter sharks than Berardius bairdii, as the known specimens showed a particularly large number of bite scars from this parasitic sharks. On the other hand the overall amount of battle scars from intraspecific fights appears considerably lesser than in B. bairdii. Here is a wonderful illustration of Berardius minimus by Jaime Bran:

Berardius minumus by Jaime Bran

Battle teeth and barnacle-plaque

Most beaked whales have a highly reduced yet also highly specialized dentition. Cephalopods and smaller fish are caught by suction feeding for which teeth are not necessary, especially as most prey items are very small. The pair of lateral throat grooves and the well-developed hyoid bone and muscles can create a strong vacuum to literally suck in prey. In general only the males have teeth, usually a single pair. Beaked whales of the genus Berardius however have four remaining teeth in the lower jaw which also erupt in both sexes, whereas the upper jaw is completely toothless.

Head detail of Berardius bairdii with the extraorally located first pair of teeth.

The first pair is located at the top of the prognathic mandible and is functionally extraoral (narwhals are not the only cetaceans with such a condition, we see this also in many beaked whales) whereas the second pair of teeth remains hidden as long as the jaws are closed. Many thanks to Sally Evans who made some great photos of a Berardius arnuxii skull at the archives of the Natural history Museum in London for me.

Berardius arnuxii skull. You can see very well the how the lower jaw is longer than the upper jaw. Photo by Sally Evans

Those teeth are used during intraspecific fights and both males and females show scars from such confrontations. In some old males nearly the whole fore half of the back consists of scar tissue. Most of the scars were obviously caused by the first pair of the antagonist’s teeth, but sometimes you can also find four parallel lines of scars as well. I still wonder how exactly they manage to produce this kind of pattern. The parallel orientation of this scars means that the attacker scratched the skin either during a forward facing movement with widely open jaws or that it tried to bite the other whale and was moving backwards.

Detail of the body with various scars. Most of them are tusk scars from intraspecific fights, the round scars are cookiecutter shark scars.

The teeth in dorsal detail view.

Detail of the mandibular teeth of Berardius arnuxii. Photo by Sally Evans.

Adding scars to an animal is usually a fun part (much of the drawing and painting time is hard and exhausting work), it gives you the chance to give it some individuality and tell some stories of its life. But the amount of battle scars in Berardius is often of such an extreme extension over the body that I decided to depict it only with a very moderate amount of scars, like we see it in younger males. Too much white scar tissue makes it hard to see the original shape and anatomy of the body.

Due to the common use, the teeth they have also often strong abrasions in older individuals and can be worn down to the skin. Because those teeth are all the time surrounded by the sea, they get colonized by shell-less goose barnacles. This is a very common thing in beaked whales with extraoraly located teeth. In Berardius it’s mainly the marginal part of the teeth near the skin where the barnacles grow like a little brush. But sometimes the barnacles grow to quite considerable sizes, forming fleshy masses that look like kelp. You can see an example of excessive goose barnacle growth here.

Massive barnacle growth on the tusks of a Baird´s beaked whale. Scan from The Canadian field-naturalist (1993). Photos courtesty of H. Omura, from Leatherwood et al. (1982: 90). Source: Wikipedia

The social life of Berardius is weird to say it at least, and could well be a chapter of its own. So I´ll refer here to Cameron McCormick´s excellent blog article which also deals with this topic.

I wrote that Berardius minimus grows „only“ to about 7 meters. But how big is Berardius bairdii? The average is about 10-11 m, where males are somewhat smaller than females. The maximum recorded length for this species is 12,7 m and the maximum weight at around 10-15 tons. This is really enormous, bigger than every orca, and they range in a similar size class as the next biggest rorquals like the Bryde whale and Omura’s whale.

Dead Baird´s beaked whale at a whaling station at Japan. Scan from The Canadian field-naturalist (1993). Photos courtesty of H. Omura, from Leatherwood et al. (1982: 90). Source: Wikipedia

Arnoux´beaked whale is somewhat smaller but still reaches lengths of 9,75 m. As a result of the extreme sexual size dimorphism of Physeter the size range of Berardius even overlap with those of female sperm whales, and large Baird’s beaked whales are even longer than average-sized female sperm whales. Berardius bairdii also fills a similar ecological niche as Physeter and mainly feeds on cephalopods and fish in the deep sea. The main difference is that its diet does not include bigger prey species like large squids or sharks. But even sperm whales feed mainly on animals which’s are proportionally tiny and really large prey like adult giant squids are usually only consumed by males anyway. So it would be really interesting to know how much both species compete in areas where they are sympatric.

Here is a size comparison of a female B. bairdii with an average female sperm whale which I made during an early version of the illustration.

So far no one has ever seen Berardius hunting but it would be an incredible sight to watch those leviathans patrolling the floor of the north Pacific and sucking in half-meter long grenadiers. That’s why I tried to create an illustration of a hunting Baird’s beaked whale to give you some idea how this could look like. Right now, when you are reading this lines, something like this happens in reality, but in pure darkness. Just think about this, we life in an awesome world.

Berardius bairdii is a comparably opportunistic hunter which feeds on a large number of very different deep sea squid and fish. Grenadier fish or rat-tails make up a big part of their diet. This fish reaches usually lengths of about a 0,5-1 meter and stay usually close to the seafloor. In many areas they are among the most numerous deep sea fishes and make up much of the vertebrate biomass. Some species are even commercially fished. But Berardius also feeds on many other species, from codlings to lancetfish.

Pacific grenadiers are among the most important prey animals of B. bairdii

From examinations of stomach contents we also know various cephalopod prey species of Berardius bairdii, even small specimens of Architeuthis (the famous giant squid) were already recorded. It seems that hunting occurs mainly close to the seafloor and Berardius can dive at least to depths of 1777 meters.

Galiteuthis pacifica

I looked for various references for the sea floor and the other animals around. The small swarm of fish chased by the whale are Pacific grenadiers (Coryphaenoides acrolepis), the small translucent squid on the right a subadult specimen of Galiteuthis pacifica which is also known from stomach contents of B. bairdii. I also depicted a grey cutthroat (Synaphobranchus affinis), a deep sea eel which is also a known prey species.

Monster carcasses

The giant size, the somewhat unusual anatomy and the unfamiliarity of many people with beaked whales in general and the transformation powers of taphonomy resulted into several cases in which carcasses of Berardius bairdii were mistaken for sea monsters. One of the most famous cases, the Moore beach carcass (featured by Darren Naish at Tetrapod Zoology), is still often claimed as the alleged relics of a modern day plesiosaur. An upside down floating Berardius bairdii was assumed to be a late surviving archaeocete (also covered at Tetrapod Zoology). Another much more recent case from 2015 gained a lot of attention in the international press. The „bird-beaked“ and „hairy“ carcass which washed ashore at Sakhalin Island was assumed to be a giant hairy dolphin, a Ganges freshwater dolphin and even the relics of a mammoth from the permafrost which was somehow washed to the sea. This identifications are all highly absurd and it´s surprising that no real experts were asked for their expertise. The size, the shape of the skull and jaws, the melon and the visible flipper bones all clearly show it was a Berardius carcass, and the „hair“ is just a very common artifact of decomposition when tissue fibres disconects from each othe. Cameron McCormick wrote also about the sometimes bizarre effects of decomposition and scavenging on Berardius carcasses. I included some of those cases also in a talk which I gave in 2018 about „monster“ carcasses, in which I presented various cases of misidentified animals which were claimed to be monsters, „dinosaurs“ or other alleged prehistoric or unidentifiable beings which – according to tabloids and internet news – baffled scientists all the time. I explained how taphonomy can drastically change the appearance of an animal’s body and why cetacean carcasses in particular are so prone to get misidentified as monsters. It was especially important for me to show how you have to systematically examine such cases for the identification from anatomical traits which are usually not affected by mere degradation of soft tissue. But that’s another topic of its own which I want to cover another time.

References:

Leatherwood, S., R.R. Reeves, W.F. Perrin, and W.E. Evans, 1982. Whales, dolphins, and porpoises of the eastern North Pacific and adjacent Arctic waters, A guide to their identification, NOAA Tech. Rept., NMFS Circular 444, 245 pp.

Ohizumi, H., Isoda, T., Kishiro, T., Kato, H., 2003. Feeding habits of Baird’s beaked whale Berardius bairdii, in the western North Pacific and Sea of Okhotsk off Japan. Fisheries Sci 69, 11–20. https://doi.org/10.1046/j.1444-2906.2003.00582.x

Walker, W.A., Mead, J.G., Brownell, R.L., 2002. DIETS OF BAIRD’S BEAKED WHALES, BERARDIUS BAIRDII, IN THE SOUTHERN SEA OF OKHOTSK AND OFF THE PACIFIC COAST OF HONSHU, JAPAN. Marine Mammal Sci 18, 902–919. https://doi.org/10.1111/j.1748-7692.2002.tb01081.x

Yamada, T.K., Kitamura, S., Abe, S., Tajima, Y., Matsuda, A., Mead, J.G., Matsuishi, T.F., 2019. Description of a new species of beaked whale (Berardius) found in the North Pacific. Sci Rep 9, 12723. https://doi.org/10.1038/s41598-019-46703-w

Veröffentlicht unter Illustration, Kryptozoologie, Tiefsee, Wale | Schreib einen Kommentar

The feathered Warsaw Dilophosaurus

Originally I wanted to continue the series about the Messel-fossils, but I am still working on a reconstruction illustration for the next part and needed a break. Instead I´ll jump on the Dilophosaurus bandwagon, because this awesome theropod from the Early Jurassic is just big in the news, and it´s a good excuse to finally post some photos about a quite unconventional yet very cool Dilophosaurus reconstruction from the Geological Museum in Warsaw. I don´t even want to go here into the details of the new publication but mainly show you some photos which I took several years ago in Warsaw:

Dilophosaurus reconstruction in the Geological Museum Warsaw. Photo by Markus Bühler

As you can see, nearly the complete body of this reconstruction is covered in filament-like feathers, quite in contrast to the common depiction of Dilophosaurus with nothing but naked scaly skin. This is btw not the first time I wrote about this species. Years ago I already discussed why the popular idea that it was just a scavenger was not really likely.

Dilophosaurus head detail. Photo by Markus Bühler

Here´s a detail of the head. It´s not that easy to see from this direction, but the artists even added some fin bristle like feathers to the head.

Dilophosaurus in frontal view with nice bristles. The crests are rather thin, but the new research has shown the were possibly much more volumous in reality. Photo by Markus Bühler

It comes already quite close to the new (and pretty awesome-looking) reconstruction by Brian Engh. Of course this version does inclued a pretty large amount of artistic freedom regarding the soft tissue reconstruction, but it looks really very interesting. Brian´s Dilophosaurus puppet is also a wonderful example how life-like well-made models can look and how superior they still are compared with most CGI attempts. Take a look at this video by Brian, which includes also some information about the news from the paper.

The appearance of the Warsaw Dilophosaurus is even more surprising given the fact that the model was created in 1997 by Marta Szubert. At that time theropods were still nearly universally portrayed without any feathers or filaments and hardly anyone considered to depict a big theropod with anything else than scaly skin.

The featherless parts of the arms and legs of the model from Warsaw were also quite nicely sculpted, especially the scale patterns of the feet looked highly realistical (more about the scale patterns on the legs of ostrichs and emus).

There was a huge amount of information which was used to create this reconstruction, for example various body impressions.

Here is another photo in full lateral view. I really love how the tail was covered in alternating black and white feathers.

In 2013 Darren Naish already wrote another blog article with some additional background information about the history of this particular reconstruction. I highly recommand to read it.

If you ever visit Warsaw, you should really take some time and visit the Geological Museum. Its paleontological section is not quite big, as it mainyl focuses on geology and mineralogy, but it´s still really worth to visit. If you want to see more fossils, including the likely best exhibition about Tarboaurus, you have to visit the Museum of Evolution, which is located in the monumental Palace of Culture.

Veröffentlicht unter Dinosaurier | 3 Kommentare

Fossil treasures of Messel Pit part II: Crocs and gators

The fauna of the area which would later become the Messel pit was quite rich in crocs. Some of them strongly resembled modern crocodylians, but some of them were oddballs which differed strongly from any extant species.

The big reptile showcase of the Messel exhibition in the Senckenberg Museum at Frankfurt

The biggest crocodylian of Messsel was Asiatosuchus germanicus, a species which is known from skulls (including the mandible length) up to about 68 cm in length. The total length was up to about 3,5-4 m, about the size of an average American alligator. The very broad and robust jaws also resemble those of an alligator, and it is likely that Asiatosuchus had a similar ecology.

Asiatosuchus germanicus skull, Senckenberg Museum Frankfurt

Asiatosuchus was also the largest animal found in the Messel pit and also the largest carnivore. In contrast to most of the fossils from the lake sediments which had to be transfered from the surounding matrix into an expoy-layer during a complex process, some of the larger croc fossils were massive enough to prep the bones completely out of the oil-shale.

Asiatosuchus germanicus skull, Senckenberg Museum Frankfurt

Here is the partially preserved postcranial skeleton:

Asiatosuchus germanicus hindquarters, Senckenberg Museum Frankfurt

The other Messel crocs were considerably smaller. Diplocynodon darwini for example, an alligatoroid, reached only lengths of about 1,5 m.

Diplocynodon darwini fossil, Senckenberg Museum Frankfurt

This species is knwon from many very well preserved skeletons.

Diplocynodon darwini fossils, Senckenberg Museum Frankfurt

Even tiny hatchlings were preserved.

Juvenile Diplocynodon fossil, Senckenberg Museum Frankfurt

Another small diplocynodontine crocodylians was Diplocynodon deponiaa (formerly Baryphracta deponia). Sadly the only photo I took was rather bad in quality, but at least you can still see one of the most noticeable traits of this species, its very well developed osteoderms:

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Diplocynodon deponiae fossil, Senckenberg Museum Frankfurt

Those crocodylians were all comparably similar to some of our modern species. But there were also very distinct forms which have no ecological equivapents today. One of them was the alligatorine Hassiacosuchus haupti (formerly Allognathosuchus haupti). This was a also a rather small animal which only grew to about 1,5 m. It had an extremely shortend snout and wide blunt mushroom-shaped teeth in the posterior part of its jaws. This indicates a certain specialization for small hard prey animals like snails, crabs or small turtles.

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Hassiacosuchus haupti fossil

The coolest Messel-croc is sadly only known from very fragmentary remains, a partial mandible and a partial skull (which was sadly not on exhibit) of a single specimen found in the shales. It was Bergisuchus dietrichbergi, a small sebecosuchian. This lineage of crocodyliforms is especially well known from South America, where they evolved a big diversity with some particularly large species. This animals were totally unlike any modern crocodylians and resembled to some degree the large predatory archosaurs from the Triassic like Batrachotomus. They were fully terrestrial and agile and long-legged hunters. Their deep jaws had laterally flattened teeth with sharp serrated edges like those of theropod dinosaurs, but with a pair of enlarge canine-like teeth in the mandible. This animals are very little known and hardly ever mentioned even in paleontology books, but for millions of years those animals were among the dominant terrestrial predators in many parts of the world.

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Cast of partial mandible of Bergisuchus dietrichbergi

Bergisuchus was not even the only terrestrial croc of Messel. Another species, originally described as Pristichampsus rollinanti but now dedicated to Boverisuchus is also known from this site, sadly only from extremely fragmentary remains, without any specimens in the exhibition. Here is a speed painting by Joschua Knüppe of Boverisuchus.

Boverisuchus by Joschua Knüppe

This animals had lesser deep jaws than the sebecosuchuians but shared with them the ziphodont meat-slicing dentition. Boverisuchus reached lengths of up to 3 m, but to the usually rather small mammals of the Messel-fauna they must have appeared like huge monsters.

In the next part I will cover the other reptiles from the exhibition.

Veröffentlicht unter Amphibien, Krokodile/Crocodylians, Museen, Paläontologie, Reptilien | Schreib einen Kommentar

Fossil treasures of Messel pit part I: Fish

The Messel pit is one of the most spectacular fossil sites of the world. It gives us an incredible insight into a subtropical ecosystem from the Eocene, about 47 million years ago. The special conditions of this Lagerstätte did not only preserve the bones of the animals which lived in and around a deep crater lake, but also in some cases hair, feathers and body silhouettes, even insects with their colors still preserved. It enables us to get a vivid view of a bygone world, from its plants to insects, fish, amphibians, reptiles, birds and mammals.

It was a weird world which consisted of the survivors of the mass extinction at the end of the Cretaceous 66 million years ago and lineages which had just started to evolve into many animals which we know today. We find a lot of animals which appear surprisingly familiar and modern to us, yet considerably out-of-place in many cases, but also weird archaic lineages and overturned experiments of evolution. In this series I want to feature some of the fossils at the Messel pit exhibition of the Senckenberg Museum at Frankfurt, which I visited in early spring, just before the country was hit by the pandemic. I don´t want to go too much into the details of the species, as this would easily go beyond the scope of this blog article.

I will start the series with the fishes from the exhibition. The most famous fish from Messel pit are quite likely the gars, which I featured already in an earlier blog article several years ago. Today we find gars only in the New World, mainly in the east of the United states, at Cuba and parts of Mesoamerica. But 47 millions years ago gars did swim also in the area which would later become Germany. Gars have interlocking ganoid scales with a very hard layer of enamal on the surface and often fossilize particularly well. The most common species of gar from Messel was Atractosteus strausi (Syn.: A straussi, A. straußi, M. messelensis and A. kinkelini):

Atractosteus strausi, Senckenberg Museum Frankfurt, photo by Markus Bühler

This is a quite common fossil of Messel pit, and you can find similar specimens in many museums around the world. It looked quite similar to modern gars, but remained much smaller than any of the extant species, usually only 20-30 cm on average and about 40 cm at maximum. This is really tiny compared to the giant alligator gar which can reach record lengths of about 3 m. Gars are quite archaic fish which differ from most other extant bony fish in a number of anatomical traits, like their ganoid scales or the heterocercal caudal fins.

Atractosteus strausi, Senckenberg Museum Frankfurt, photo by Markus Bühler

Here is another fossil, fully prepped out of the surrounding matrix:

Atractosteus strausi, Senckenberg Museum Frankfurt, photo by Markus Bühler

Besides A. strausi we find also another small, yet considerably weirder gar, Masillosteus kelleri. It was somewhat bigger than A. strausi and differed from all extant gars in its short and robust jaws which were not adapted to feed on fish but to crush hard-shelled invertebrates with its big and flattened teeth. Sadly there were no fossils of this species on display, but you can see a great life reconstruction of A. strausi and M. kelleri by Joschua Knüppe here:

Fossil gars of Messel pit by Joschua Knüppe

Besides the gars was also another primeval predator, the amiid Cyclurus keheri:

Cyclurus keheri fossil, Senckenberg Museum, Frankfurt. Photo by Markus Bühler

Amiids are a very ancient lineage of bony fish and are not very closely related with any other modern fish. Like the gars they have a heterocercal caudal fin. It was the large fish of this waters and large specimens reached lengths of around 70 cm.

Cyclurus keheri fossil, Senckenberg Museum, Frankfurt. Photo by Markus Bühler

In the Mesozioc there was a huge diversty of amiids, but today there is only one single remaining species, the bowfin (Amia calva) which is restricted to the North American continent. Besides its unusual caudal fin it doesn´t really look particular primitive, but it´s nearly some kind of freshwater analogue of the famous coelacanths of the genus Latimeria. Cyclurus keheri was quite similar to the modern bowfin in appearance, perhaps a little bit stockier. Here is a photo of a modern member of Amia calva by Arthur Kosakowski for comparison:

Modern bowfin (Amia calva), photo by Arthur Kosakowski

Take a close look at the fossil and its well developed teeth, which are very similar to those of the modern bowfin. They aren´t visible in the living fish, because they are hidden by the fleshy lips. Without living relatives for comparisons, we would quite likely only see quite toothy life reconstructions of it. Here is also another nice photo of a juvenile bowfin by Kurtis Smith:

Juvenile bowfin (Amia calva), photo by Kurtis Smith

We know similarly sized specimens from C. keheri from Messel, and tiny gars as well:

Fossil eel, juvenile bowfin, Thaumaturus intermedius and juvenile gars. Senckenberg Museum, Frankfurt. Photo by Markus Bühler

The small fish below the bowfin is Thamaturus intermedius. Its taxonomical relations are still somewhat problematic, some of the sources I found say it was related with mooneyes, whereas other sources say it was a member of the Salmoniformes. There are only two remaining species of mooneyes today, which also live solely on the North American continent today, but have a good fossil record from other continents as well. Despite their unremarkable appearance they belong to a quite archaic lineage and have some quite interesting relationships with the Osteoglossiformes which include such remarkable species like arapaimas or arowanas.

On the left you can see a fossil of the eel Anguila ignota, which is the rarest of all fishes from Messel pit, known only from a single specimen.

The ichthyofauna of Messel pit is quite low in species number and appears surprisingly unexotic, unlike the oddballs which we find among the rest of the contemporary fauna (more about them in the next parts of the series). What I find really interesting is that it includes so many lineages which are now restricted the New World, North America in particular.

Another predator was Amphiperca multiformis, a small but particularly large-headed and big-mouthed perch with a deep body, which looked a bit like a small and shortened version of a warmouth (Lepomis gulosus).

Fossils of Amphiperca multiformis, Senckenberg Museum, Frankfurt. Photo by Markus Bühler

I made a simple speed-painting based on a skeletal drawing of Amphiperca. I usually spend much more time to make fine details and such things, but this time I really only wanted a quick illustration which was done in little more than an hour. I used some color morphs of the highly variable warmouth as main color reference. The fins of this fish are folded, because it´s directly based on the fossil of a dead fish. When the fish was still alive they were of course flexed and looked slightly different, but I wanted to stay as close as possible to the actual proportions of the fossil, so I didn´t try to reconstruct them in a different shape.

Speed-painting reconstruction of Amphiperca multiformis by Markus Bühler

There is also another small perch known from Messel pit, Palaeoperca proxima, whose fossils are however not as common as those of Amphiperca. It was about 20 cm in total length and had a more elongated body than Amphiperca and the two dorsal fins were distinctly separated. Its proportionally much smaller mouth indicats that it also mainly feed on comparably small prey. Sadly there were no fossils of this species on display. The next part of the Messel pit series will cover the reptiles.

Veröffentlicht unter Evolution, Fische, Paläontologie | Schreib einen Kommentar

Shit happens part IX: The fatal snake hunger of a grebe

Bizarre deaths and accidents of animals were already covered for several times on the blog, especially in the shit happens-series. Today I want to feature an interesting specimen to continue this topic. This is a partially dissected great crested grebe (Podiceps crestatus) which was found dead, after it tried to gobble an adult European grass snake (Natrix natrix).

Great crested grebe which suffocated while trying to swallow a European grass snake. From the collection of the Senckerberg Museum at Frankfurt. Photo by Markus Bühler

I appears that the snake´s body somehow formed a knot around the grebe´s lower jaw, with fatal effects for both opponents. Great crested grebes usually prefer much smaller prey items like small fish in the range of 10-15 cm, sometimes also amphibians and invertebrates. The normal maximum length of their prey is about 25 cm, so this grebe was particularly enthusiastic when it trid to swallow a whole grass snake which likely exceeded its own body length. You can even see the snake´s head in the opened stomach:

Head of the grass snake in the opened stomach cavity of the grebe

The snake inside the grebe

To give you a better idea of the size of the snake inside, I´ve tried to make a simple reconstruction of it. I have to emphasize this is really just a speculative reconstruction, without an X-ray image it´s hard to say how exactly the snake was curled inside the stomach and perhaps the curve I expected for the snake´s body inside the grebe´s esophagus was not curved enough. But anyway, here it is:

Reconstructed grass snake inside the grebe

The tragic death of the grebe and the snake aside, we see here also an interesting example how unpredictable animal behavior can be. Who would have expected that a grebe would try to attack a snake which is several times as long as its usual maximum prey size for example?

The dissected grebe sadly doesn´t really show the beauty of this elegant kind of waterfowl, so I wanted to finish this blog entry with a somewhat lesser macabre photo. I see grebes comparably often in the wild, but they are usually too shy and too far away to take good photos of them. But several years ago I managed to take some better close-up photos of some grebes at Lake Garda.

Great crested grebe, Lake Garda. Photo by Markus Bühler
Veröffentlicht unter Reptilien, shit happens, Vögel | Schreib einen Kommentar

The rasping Mouth of Death

I haven´t posted new stuff on the blog since quite some time, but not because I´m no more writing, but due to the amount of work which is going into some future blog articles. For that reason I was looking for something interesting I could post until the next bigger article is finished. I found a really interesting photo of the mouth of a sea lamprey (Petromyzon marinus) from the Zoological Museum at Kiel at my archive. It looks so wonderfully monstrous yet disturbingly aesthetic for its sheer obvious efficiency that I just had to share this:

Mouth of a sea lamprey (Petromyzon marinus), Zoological Museum Kiel

Sea lampreys are the largest lampreys and can reach lengths of over 1 meter, but usually stay within the range of 70-90 cm. The adult sea lampreys make living as parasites of larger fish, which they attack with their sucker-like mouths and keratinous pseudoteeth and tongue. They rasp and cut pieces out of the fish´s skin until they reach the underlying tissue, so they can suck the effluenting blood, lymph and shreds of tissue.

They became especially infamous after they invaded the Great Lakes and caused havoc among the populations of local fish like lake trouts (Salvelinus namaycush). Here is a taxidermy cast of a namaycush with an attached sea lamprey from Redpath Museum, Montreal:

Sea lamprey attacking a lake trout, Redpath Museum, Montreal.
Veröffentlicht unter Fische | 2 Kommentare

The weird little whales that hide within a cloud of their gut fluid

Many animals have developed amazing anti-predator adaptions, from mimicry to the ability to autotomize certain parts of their own bodies. One of the most bizarre defense mechanisms among mammals is found in the two exant members of the genus Kogia, the pygmy sperm whale (Kogia breviceps) and the dwarf sperm whale (Kogia sima). This dolphin-sized relatives of the enormous sperm whale (Physeter macrocephalus) evolved a method to confuse predators which is…well… special.

Pygmy sperm whale (Kogia breviceps) hiding in a cloud of rectal fluid © Markus Büher

Both pygmy and dwarf sperm whales are comparably slow and often bask motionless near the surface. This makes them an easy prey for predators like great white sharks or orcas, which were already found with Kogia remains in their stomaches. They were rarely and just very locally targeted by human hunting activities, for example off Japan, but their passive behavior on the surface made them also an easy target for whalers who could easily harpoon them from nearby boats. When harpooned, they were observed to emit a reddish-brown fluid from their anus which formed a cloud in the water. For this reason they are called Tsunabi in Japanese, a name that can be translated to something like „firecracker-whale“. Sometimes this fluid also leaks out of the anus of stranded specimens, what lead to their Sri Lankan name lie mulla, what means „blood dolphin“. The cloud formed by the dark fluid can apparantly be up to about 100 square meters in size.

This fluid is stored within an a unique sac-like bulging of the lower intestines which can hold up to about 12 l in large specimens of K. breviceps. The consistency of this reddish-brown fluid was compared with chocolate syrup (keep this in mind if you eat chocolate syrup for the next time…), but it can be also have a more granulous sand-like structure that dissolves in the water. Despite its location within the lower intestines it doesn´t seem to be just of fecal origin. It was already found in a foetal K. breviceps and a new-born and still un-nursed K. breviceps, what indicates that this substance which contains large amounts of carbon (up to more than 60%) is not just a digestion-by-product of their cephalopod-rich diet but is synthesized in the guts.

Pygmy sperm whale (Kogia breviceps) skeleton of a specimen found in the gulf of St. Lawrence. Centre d’interprétation des mammifères marins, Tadoussac. © Markus Büher

In one case a female K. sima and her calf were together with several dolphins accidentally caught in a net for tunas in the eastern tropical Pacific. The dwarf sperm whale emitted dark reddish fluid and tried to hide in the cloud whenever one of the dolphins approched it or the calf. This happened for several times, what also means that they usually don´t realease the full storage of intestinal fluid at once. This mechanisms, which appear to work in similar way as the inking of cephalopods, irritates the attackers optical and sensorical senses. This would also work in the dark waters at depths of 100 m and more where K. breviceps and K. sima usually hunt, because the olphactorical irritation would still work against sharks. I am not aware of any other depictions of the inking of Kogia, what also encouraged me to create an illustration of this bizarre behavior. Possibly it´s even the first published depiction, but I recently learnt that my good friend Julius Csotonyi also created somewhat earlier an illustration of this behavior for an upcoming book about cetaceans.

Here is also a video which shows a dwarf sperm whale which was chased by a fur seal at Hout Bay Harbour, Cape Town. The dwarf sperm whale released its gut fluid, which immediately produced a huge cloud within the surrounding water:

The reason why kogiids evolved this unusual defense mechanism is possibly linked to heavy predation, which could have an even more severe impact on their populations than we know from direct evidence. Pygmy and dwarf sperm whales have short life cycles and practice some sort of live-fast-die-young-way of life. They are sexually mature at 2,5-5 years, females have (unlike Physeter) a comparably large number of offspring during their lives and they ususally don´t live particularly long. This could also explain why they evolved such a special way to compensate their low speed and agility as a mean to escape from predators. Surprisingly, a similar behavior of releasing a cloud of „fluid“ was also recorded in Physeter as a response of stress, like approaching whalers or orcas. As they lack the sac-like bulge of Kogia to store a fluid, it´s likey that they really just release their feces however. This also indicates that this behavior have evolved already at comparably basal sperm whales.

Sources:

Ellis, Richard (2011). The Great Sperm Whale: A Natural History of the Ocean’s Most Magnificent and Mysterious Creature. Zoology. 179. USA: University Press of Kansas.

Plön S. The status and natural history of pygmy (Kogia breviceps) and dwarf (K. sima) sperm whales off southern Africa, PhD thesis. Grahamstown: Rhodes University; 2004.

Willis, P. M., and R. W. Baird. 1998. Status of the dwarf sperm whale, Kogia simus, with special reference to Canada. Can. Field-Nat. 112:114–125.

Veröffentlicht unter Blogposts in English, Säugetiere, Wale | 2 Kommentare

A tiny tusk within a broken tusk – just another narwhal oddity

The narwhal Monodon monoceros is almost a real-life fantasy creature. But not only due to its historical connection with the legendary unicorn – after all, a whale with an enormous tusk growing out of its head is much more fabulous than most legendary animals from ancient bestiaries which don’t even exist. If we would know narwhals only from fossils, we would surely deeply regret that we could never see this marvelous beast alive. But this creature – one of the most bizarre cetaceans which ever evolved – is an extant species and a good reminder that we still live alongside many incredible animals which can easily compete with the most extraordinary beasts of prehistoric times. There is a lot to say about narwhals, and it would be probably easy to write even a whole book only about their iconic tusks. I recently wrote about their rarely shown vestigial right tusks and a bizarre hybrid between a female narwhal and a male beluga.

Much about the exact function and use of the large torqued tusks still remains an enigma. Many assumptions about the functional use were based on examinations of the anatomy of the tusks, their surface, abrasions and wear patterns. Actual observations of active tusk usage are still extremely rare. A recent video shows that it has apparently really an assisting function for hunting however. But as usually only males possess fully developed tusks, it seems obvious that it has a role for sexual competition as well. Broken tusk tips found embedded into the skull bones of other males indicate that narwhals use their enormous teeth for physical interactions with other males as well.

One of the weirdest phenomena you can find within the cetacean literature are cases of broken narwhal tusk tips inside broken narwhal tusk tips. Errmmm…. What!? To avoid further confusion, I will show you some examples from which I took photos at the University of Copenhagen Zoological Museum.

University of Copenhagen Zoological Museum. Photo Markus Bühler

There are three of such tusks on display, however one of them is just a short fragment.

University of Copenhagen Zoological Museum. Photo Markus Bühler

There is a considerable part of the tips broken off, and you can see the cavity which was originally filled by the pulp. And within this cavity is a plug of torqued ivory, which perfectly fills the opened tusk.

University of Copenhagen Zoological Museum. Photo Markus Bühler

There are also longitudinal fractures and some bending of the tusk around the plug, and it looks like it was forcefully pierced into the broken end.

University of Copenhagen Zoological Museum. Photo Markus Bühler

So what happened here? Was there a narwhal with an already broken tusk tip seeking help by Dr. Monodon who used its own tusk in an altruistic attempt to fill the aching fracture with its own tusk and break the tip off? Or to stay more seriously, could it be that it happened by accident that a male narwhal rammed its thin tusk tip during an interaction in the already fractured tusk of an opponent? Or could it be that narwhal bulls touch each others tusks and one tip became by chance plugged into the opening of the fractured tusk?

University of Copenhagen Zoological Museum. Photo Markus Bühler

It really appears that something like this was happening, and the very existence of not just one but three such cases in a single museum could indicate some never observed behavior. However, as interesting as the idea of narwhal bulls accidentally practicing some sort of endodontic treatment to each others tusks appears, those broken tusks have a quite different background. It started with a tusk fracture, perhaps when a narwhal hunted fish on the sea bottom and had a traumatic collision with a rock. The tip of its tusk broke off, leading the whale quite likely in severe agony for some time. If something similar happens to a human, for example when an incisor is fractured and the pulp becomes exposed, it is just a matter of time until the pulpal tissue becomes infected by bacteria and necrotizes, at least if it is not properly treated. Under totally aseptic conditions – something only possible under laboratory conditions with totally germ-free mice or rats in an isolated environment – the exposed pulpal tissue can produce again new dentine at the fracture and seal the wound.

Fractured narwhal tusks can heal in a similar way without the usual necrotizing of the whole pulp and the resulting fatal conditions for the tusk. Perhaps this is due to the extreme size of the pulp and the many blood vessels within that lead to a better exchange of immune cells and lead also to a faster regeneration of the ruptured tissue. The seawater which always surround the wound might help as well. But admittedly, this is nothing but my personal speculation. It’s noteworthy that exposures of pulps in orcas – something quite common in captive specimens and those which specialize in hunting sharks and skates with highly abrasive skin – lead to necrosis of the pulps as well.

But narwhals can heal such fractures. When the cells at the outer area of the pulp-wound manage to produce a new formation of dentine the fracture is sealed. But this layer is apparently not tightly attached to the inner walls of the tusk. For this reason the ongoing apposition of reparative dentine forms over time a twisted plug which is pressed out of the pulp cavity, forming over time a tiny new tusk. And this is what appears to be the broken tip of a tusk rammed into the open pulp. The crack and bending of the fractured end were possibly also a postmortal artifact when the tusk dried.

I found the information about the reparative dentine of the broken narwhal tusks in the 2003 edition of Walker´s Marine Mammals of the World by Ronald M. Nowak. I was sadly not able to track down the original sources of Reeves, R.R., and S. Tracey.1980. Monodon monocers. Mammalian Species, no. 127, 7 pp and Newman, M.A. 1978. Narwhal. which was cited in Haley, D., ed. 1978. Marine mammals of eastern North Pacific and Arctic waters. Pacific Search Press, Seattle, 138-44. If anyone reading this has access to this original sources or any other information about this topic, I would be quite interested.

Veröffentlicht unter Anatomie, Blogposts in English, Teratologie, Wale | Schreib einen Kommentar

The bird that follows in the footsteps of the dinosaurs

Technically, all modern birds are dinosaurs, descendents of a lineage of theropods that evolved complex feathers and the ability to fly. But to be honest… most of them don´t really look very „saurian“ anymore. Those fancy feathers, toothless beaks and stumpy tails – usually coupled with a small overall size – just make it sometimes hard to accept their family background. Even if you know that filaments and feathers were in fact a quite common thing among dinosaurs, even if you are well aware of the fact that a lot of dinosaurs were of quite small body size and even if you are quite familiar with the evolutionary origins of modern birds you can still struggle to accept birds as real living dinosaurs. But sometimes you get a reminder about their theropod heritage, and a glimpse into a time when their ancestors were still not trying to conquer the airspace. For example if you take a close look at one of the largest extant birds, the emu Dromaius novaehollandiae. Don´t look at its pretty blue head or the shaggy double-feathers. Just look down at its staggering feet.

The foot of an emu. Photo by Markus Bühler

There is probably really nothing closer to a non avian theropod foot in the modern world. This is how people even today usually imagine a classical theropod foot. If you forget the rest of the body, you can really easily imagine that it belongs to something much more primordial, somethat that had still jaws lined with teeth, arms with big claws and a long tail. Of course there are some anatomical differences, for example the missing hallux of the emu. But it is still pretty awesome that something still walks the earth on such feet.

The ostrich has even bigger feet, but they are unique and utterly bizarre by nearly every standard, the feet of the cassowary are also pretty cool, but with their elongated claws still somehow too non-standard and not really that similar to any dinosaur feet. It it really frustrating that we missed some of the most spectacular birds that ever lived – the giant moas of New Zealand and the elephant birds of Madagascar – for just a few centuries. The feet of this giant birds were quite likely even closer to the feet of a medium-sized non-avian theropod than anything alive today.

I wrote some time ago about the incredibly polymorphous scales on the feet and legs of the ostrich. If we look at the feet of the emu, we can also see some quite interesting anatomical features as well.

Some of the scales on the backside of the tarsometatarsus form massive conical structures. I have to admit that I have no idea what function they have. But those cone-scales are surely something nobody would expect to have ever existed by looking at the bare bones of a fossil. I can´t help, but they could look pretty cool on the legs of a non-avian theropod as well.

The conical scales on the backside of an emu leg. Photo Markus Bühler

Should I ever get my hands on the foot of an emu, I will try to make a similar listing of its scale types and scale arrangements as I did for the ostrich. I can´t emphasize enough how important and helpful it is to look at the anatomy of living animals to reconstruct species which we know only from their bare bones. You will discover a lot of things which you possibly never noticed before, like in the case of the ostrich and emu those weird scale shapes, the volumous pads on the downside of the toes or the way in which the nails abrade. It will also remind you that we are still living in a world full of amazing animals, and that even many familiar species are much more fascinating and unusual than most people think.

Veröffentlicht unter Dinosaurier, Vögel | 1 Kommentar