Fig. 21.—Fossil Limb bones of the Giant Sea Tortoise, Protostega gigas.
Collected by Charles Sternberg.
In 1903 I was so fortunate as to find a practically complete skeleton of Protostega gigas in normal condition, that is, with the bones all in or near their original positions. The late Dr. J. B. Hatcher, whose death in the very noonday of his glorious career as a fossil hunter cast a gloom over the world of paleontology, purchased this specimen from me for the Carnegie Museum. It has been described in the Memoirs of the Carnegie Museum by Dr. G. R. Wieland, the authority on extinct turtles, under the title “The Osteology of Protostega.” He says, on page 289: “The third of a century which elapsed since Cope’s discovery of Protostega gigas, has not sufficed to bring forth a complete restoration of any single individual of these great sea-turtles. How welcome then has been the discovery during the last two years by Mr. Charles Sternberg in the Niobrara Cretaceous of western Kansas, of the nearly complete specimens of Protostega gigas which permit the present description of the organization of the limbs, the most important of the parts yet undescribed as well as the very least likely to be recovered in complete form.” (Fig. [21].)
This rare fossil was briefly mentioned by Professor Osborn also in Science as a “complete skeleton of Protostega which lay on its dorsal surface with fore limbs stretched out at right angles to the median line of the carapace, measuring six feet between the ungual phalanges.”
A second specimen, which I discovered and sold directly to Dr. W. J. Holland, the director of the Carnegie Museum, is thus described by Dr. Wieland on page 282 of the Memoirs, under the heading “Specimen No. 1421, Carnegie Museum Catalogue of Vertebrates”:
“This fine fossil is from the Niobrara Cretaceous of Hackberry Creek.” (I should like to correct this mistake. It was found about three miles northwest of Monument Rocks in a ravine that empties into the Smoky, east of where Elkader once stood.) “The ex situ portions of the original skeleton, which had weathered out and are secured in more or less complete condition, include the left humerus, radius, ulna, etc. The in situ portion consists of the right anterior part of the skeleton, and was secured on a single slab of matrix, in which it still remains intact, as shown in the accompanying drawing by Mr. Prentice, including the lower jaw in oblique inferior view, the skull, the T-shaped nuchal (plate) and two marginals. It will be seen what exceedingly satisfactory information is furnished by the present specimen as compared with all other examples of Protostega hitherto found. Specimen 1420 [my first specimen] is more complete than any other at present discovered. As originally embedded in its matrix of chalk, nearly every element was present in an exactly or approximately natural position. Unfortunately, the collector of this surprisingly complete fossil, in an attempt to remove and separate the bones from their original matrix of chalk, mismarked some of them, and also made it impossible to either replace more than a few of the marginal elements, or to determine the outlines of any of the plastral elements. Such work is difficult enough in well-equipped laboratories. However, none of the bones of the limbs are broken, and Mr. Sternberg redeemed himself by discovering and securing in such excellent condition No. 1421, as just related.”
I learn from one of the Museum’s staff that this specimen is to be mounted this summer of 1908, and placed on exhibition. As long as the Carnegie Museum stands, this splendid example of the great sea-tortoise will be admired by lovers of nature. In shape it is very like the present-day turtle of the Mediterranean. Its huge front paddles, with a span of ten feet, were armed with horrid claws. The hind ones were stretched out parallel with the body and used as sculls by this “boatman of the Cretaceous.”
An account of my work in the Kansas Chalk would not be complete without some mention of my discovery, in several small localities, of the crinoid Uintacrinus socialis Grinell. According to Mr. Frank Springer, our noted American authority on this subject, only seven localities were known in 1901; he did not know of my discoveries. I can bear witness with him, though, to the rarity of this species. During the fifteen years in which I have gone over the chalk exposures again and again, I can remember only three localities of these fossils, the Martin locality, another three miles to the east of it, and a third on Butte Creek near Elkader. The first has yielded the finest specimens among those which were described by Mr. Springer in his magnificent treatise on Uintacrinus, published by the Museum of Comparative Zoology at Harvard University.
Last year, however, my son George found two splendid specimens about fifty feet apart, further east than they had been discovered before. The locality is south of Quinter, in the southern part of Gove County, thirty-seven miles east of the Martin locality. These two colonies each contained about forty calices. As usual, they are flattened out on the under side of a calcareous slab about a quarter of an inch thick and beveled off as thin as paper at the margins. One slab was sent to the Senckenberg Museum in Germany, while Mr. Springer secured the other.
The calyx, or as we have called it, “the head,” has ten long arms, some of them about thirty inches long.[[1]]