Our Sea Dragon – Plesiosaur – is off to the Bruce Museum, Greenwich

The Joe Webb Peoples Museum has a large collection of Ward’s casts of fossils. In 1871, more than 900 were bought by Orange Judd for exhibit in the new museum. Many were lost after the closure of the original Wesleyan Museum of Natural History in 1957, but a set of casts of plesiosaurs and ichthyosaurs were stored in the Exley Penthouse, from where we retrieved them and restored them (see blogs: Swimming with Monsters; Restoration: Terror of the Oceans). They are exhibited on the 4th and 3d floors of Exley. 

One of our larger casts is No. 225 in the 1866 Ward’s ‘Catalogue of Casts of Fossils from the Principal Museums of Europe and America’, which is given the name Plesiosaurus dolichodeirus, Conyb.  The catalogue says (figure from the catalogue below):

Skeleton on slab. The Plesiosaurus was first discovered in 1823, by Conybeare and De la Beche. Cuvier thought its structure the most singular and its characters the most anomalous that had been found amid the ruins of a former world.” To the head of a Lizard (wrote Buckland) it united the teeth of a Crocodile, a neck of enormous length, resembling the body of a Serpent, a trunk and tail having the proportions of an ordinary quadruped, the ribs of a Chameleon, and the paddles of a Whale.” The skull is three times longer than its breadth, and subcompressed. The cranium is quadrate ; nostrils small and situated near the eye ; teeth slightly recurved, striated, sharp, long, and slender, lodged in distinct alveoli,the anterior being the longest. The swan-like neck consists of from twenty to forty vertebrae, while living Reptiles have not over nine cervicals. The pectoral arch is remarkable for the greatly elongated and broad coracoid bones. The clavicle is united to the scapula as in Chelonia. Next to Turtles, the P. exhibits the greatest development of abdominal ribs. The ribs are articulated as in Lizards. The digits of the fore-paddle support respectively 3, 5-7, 8 or 9, 8, and 5 or 6, phalanges ; those of the hind-paddle have 3, 5, 8 or 9, 8, and 6. The P. differs from the Ichthyosaurus in being pentadactylous, in having a long neck, longer and more flexible paddles, a shorter tail, vertebras longer and nearly flat with two pits on the under-side, and more slender teeth. The latter is generally found lying on the side ; the former, extended on its back. The P. dolichodeirus is characterized by its extremely long neck and very small head. The proportion of the parts is nearly thus : taking the head as 1, the neck will be 5, the body 4, and the tail 3 ; the whole length being thirteen times that of the head. The four paddles are equal in size. This specimen from the British Museum was discovered in the Lias at Glastonbury, England. Size, 6 ft. x 2 ft. 9 in. Price, $18.00′.

The original specimen was collected by the Glastonbury collector Thomas Hawkins (1810-1889), whose ‘lurid geological writings‘ ‘are often dismissed as the outpourings of a lunatic‘ (R. O’Connor, 2003, Thomas Hawkins and geological spectacle, Proc. of the Geologists Association, 114, 227-241). The specimen was figured in the famous book by Hawkins, published in 1840, with the title ‘Book of the Great Sea Dragons, ichthyosauri and plesiosauri, Gedolim Taninim of Moses, Extinct Monsters of the Ancient Earth, with Thirty Plates copied from skeletons in the author’s collection of fossil organic remains (deposited in the British Museum). The frontispiece of this book is one of my favorite antique reconstructions of fossil life:

Plate 23 in this book shows the specimen, which Hawkins named as ‘Plesiosaurus triatarsostinus‘; it is easily identified through the missing left front flipper (the specimen is lying on its back), and the offset in its tail. The specimen was given number BMNH 2018* when it was donated to the British Museum.

As with so many of the large vertebrate fossils first described in the 1800s, the ‘official’ name, consisting of the genus and species name’, has gone through many variations. The very first publication of its name was by Hawkins, who in 1834 gave it the name ‘Plesiosaurus triatarsostinus‘. According to todays’s rule of taxonomy, that name should have been the valid, accepted one, but these rules did not yet exist in the 1800s. Owen argued in 1838 that Hawkins was wrong in his story about how many foot-bones the animal had, and renamed it Plesiosaurus Hawkinsii. Such a renaming would now not be accepted, but became accepted through ‘long useage’, with the name etymologically corrected to Plesiosaurus hawkinsi in 1869 (the correction also would not be valid today). The species Plesiosaurus hawkinsi was then chosen as the type species for the new genus Thalassiodracon (Ancient Greek for Sea Dragon) in 1996. The ‘plesiosaurs’ from the location in Street, Somerset (close to Glastonbury, UK) are now generally seen as older by several millions of year than the ‘real’ plesiosaurs as described from Lyme Regis in Dorset, UK (for instance, by Mary Anning). The most common plesiosaur relative in Somerset is the animal formerly called Plesiosaurus hawkinsi, and it was assigned to the genus Thalassiodracon (Storrs, G. W., and Taylor, M. A., 1996. Cranial anatomy of a new Plesiosaur genus from the lowermost Lias (Rhaetian/Hettangian) of Street, Somerset, England. Journal of Vertebrate Paleontology, 16, 403-420).  Plesiosaurus dolichodeirus was found by Mary Anning in 1823 in Lyme Regis, and was described by Conybeare in 1824 (W D Conybeare, “On the Discovery of an almost perfect Skeleton of the Plesiosaurus”, Transactions of the Geological Society of London S2-1, 1824). Note that Ward (text cited above, from the catalogue) as most people in the 19th century, did not mention the fact that the specimen had in fact been found by Mary Anning, who prepared the first description and drawing, as shown in this link. Plesiosaurus dolichodeirus from Lyme Regis is the type species of the genus Plesiosaurus, and the specimen from which Ward made his cast, found by Hawkins, thus was not a Plesiosaur, but the older genus Thalassiodracon.

Our cast of the sea dragon Thalassiodracon hawkinsi was removed from its location on the wall of the third floor of Exley, and is traveling to The Bruce Museum in Greenwich, CT. The recently renovated museum is planning an exhibition entitled “Unraveled: Natural History’s Greatest Hoaxes“.  Curator Daniel Ksepka told us that the exhibition will present classic examples such as Piltdown Man and the FeeJee Mermaid, and discuss the motivations behind the perpetrators and how scientists eventually debunked each hoax.  Our plesiosaur cast will be part of a display centered around the Loch Ness Monster, and will be an object to make a link to the discussion of how the geology of Scotland rules out the possibility of any large marine animal having migrated into the lake. The show is tentatively scheduled to run September 2023 though February 2024.