Bird art and watching, bird identifications

Retro vs Modern #08: Helicoprion davisii

First discovered in Western Australia in the mid-1880s, the bizarre-toothed eugeneodont cartilaginous fish Helicoprion davisii was initially mistaken for a species of the equally weird Edestus. It was eventually recognized as part of a separate genus over a decade later, when similar fossils of its close relative Helicoprion bessonowi were found in the Ural Mountains.

1890s-2000s

With Helicoprion only known from strange buzzsaw-like spiral whorls, the function and location of this structure in the fish’s body was a huge source of confusion for over a century.

The earliest interpretation was a defensive structure curling upwards from the snout, then as part of the tail or dorsal fins. It was soon realized to probably be part of the lower jaw instead, but the exact arrangement was still a mystery.

A downward-curling position was popular in reconstructions for much of the 20th century. From the 1960s onwards, however, discoveries of preserved skull cartilage and soft-tissue body outlines of other eugeneodont species began to give a better idea of what these fish were and what they looked like. They were identified as being related to modern chimaeras, but with a very different appearance – they had streamlined shark-like bodies with large triangular pectoral fins, a single dorsal fin, no pelvic or anal fins at all, and broad keels along the sides of their tails.

A single tooth whorl sat in the middle of the lower jaw, with its sides covered by skin, and the largest and youngest teeth formed at the back before spiralling forwards, downwards, and inwards.

In the 1990s a “pizza-cutter” reconstruction gave Helicoprion long narrow jaws with the whorl positioned very far forwards, sawing and crushing prey against the underside of the snout. A version with the whorl very deep inside the throat was also proposed in 2008, but only a year later a new variant of the pizza-cutter saw-jaw model suggested the presence of a specialized “pocket” in the upper jaw lined with teeth.

2020s

Finally, in 2013, CT scanning of a Helicoprion specimen originally discovered in the 1960s revealed something incredibly special – an almost complete three-dimensionally preserved and articulated set of jaws. It showed narrow jaws that were shorter than the previous reconstructions, with the whorl occupying the entire lower jaw and braced by cartilage on each side.

We now know Helicoprion davisii was found worldwide during the early-to-mid Permian, about 272-268 million years ago, and based on some of the biggest known tooth whorls it may have reached sizes of up to 8m long (~26’), similar in size to modern basking sharks. It continuously added new and larger teeth to its whorl throughout its life, with the smaller older teeth being retained instead of shed, slowly pushed into a tight spiral deep inside the lower jaw.

The upper jaw formed a sheath-like pocket lined with a “pavement” of numerous tiny rounded teeth, and as Helicoprion closed its jaws the various parts of the whorl simultaneously grabbed, sliced, and pulled prey further into its mouth – a mechanism possibly specialized for efficiently de-shelling cephalopods like ammonites and nautiloids.

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Allen & Ginter cigarette card, 1888

Allan Brooks (circa 1936)

From "Die Nordamerikanische Vogelwelt" by Henry Nehrling, 1891

Taxidermied quagga foal (female) from the Iziko South African Museum in Cape Town. [x]

This specimen was originally obtained in the late 1850′s. It was re-mounted in 1960 by the late Reinhold Rau (far right in photo) who founded The Quagga Project with the hopes of “breeding back” the extinct quagga. [x]

The deer of the elf King Thranduil in the movie “The Hobbit” is a reconstruction of a real-life bighorn deer, or Irish elk, which became extinct about 7,600 years ago. Outwardly, they were similar to fallow deer, distinguished by their large stature and huge (up to 4 m in span) horns. They were distributed in Europe, Asia, North Africa, as well as in Central Russia.

Netsuke (根付) are miniature carved sculptures which were very popular accessories in Japan during the Edo period (17th century). Traditional netsuke were made of materials such as wood or ivory.

just wanted to show you guys Him <3 

6th Mass Extinction

These Caribbean monk seals, also known as West Indian seals (Neomonachus tropicalis) were received by the New York Aquarium in 1909 and featured in an article from the Zoological Society Bulletin (New York Zoological Society):

"The West Indian seals which were received at the Aquarium in June, 1909, still constitute the most noteworthy exhibit in the building.

The possession of three nourishing specimens of a large species near the verge of extinction, is a fact both interesting and important. These seals are the only ones of their kind on exhibition anywhere and may be the last that will ever be seen in captivity.

In the time of Christopher Columbus, this seal was abundant in many parts of the West Indies, its range extending eastward from Yucatan to the Bahamas, Hayti, Cuba and Jamaica. It was gradually exterminated for its oil and skin, and is at the present time known to exist only on the Triangle and Alacran reefs off Yucatan. The West Indian Seal (Monachus tropicalis), is closely related to Monachus albiventer of the Mediterranean, the seal of the ancients, a living specimen of which was exhibited at Marseilles in 1907. Both species are nearly exterminated and with their disappearance the genus Monachus will be classed with the extinct animals.

The Aquarium seals will not live forever, and by the time they are gone the man with the gun will more than likely have finished off the remnant of the race in Yucatan. Our seals have not posed to the best advantage for the photographer, but the photographs reproduced in the present Bulletin, represent so far as we know the only ones in existence of the living animal.

The photographer has been requested to try again, so that the scientist of the future may have all possible documentary evidence as to the general appearance of the animal in life, and its actual existence as late as the year 1910. These seals, an adult male and two young, are not altogether pleasant as near neighbors, their harsh voices penetrating to every part of the building. The West Indian seal is, so far as our experience goes, the only member of the Phocidae or earless seals, that uses its voice in captivity.

The two young seals, a male and a female, have been growing amazingly during the nine months of their life in the Aquarium. They take a fair amount of exercise in the pool, but after being fed usually haul out on the platform along with the large male for a nap, all three huddling close together.

A "modern style" dodo reconstruction from the Naturhistorisches Museum in Vienna. [x]

Native to Mauritius and La Réunion, the dodo died out at the end of the 17th century. This reconstruction was made from the few existing drawings as well as molds of its head and feet. Parts of ostriches, swans, eared pheasants, and geese were also used.