The subject of undiscovered aquatic, subterranean or terrestrial animal life throughout the world is a topic receiving an increasing amount of attention by scientists and the lay public alike. New species are constantly being discovered from remote areas in such familiar places as Vietnam, to the depths of the Amazon River in South America, resulting in the verification of local legends, oral traditions and myths of various indigenous peoples.
Cryptozoology for example, the scientific term for such investigations, has been quite popular for many years, in its attempts to search out, document, and authenticate, the existence of previously undiscovered or rare fauna or life-forms.
Early Native-American legends & traditions are filled with accounts of strange and often savage animals, which the various tribes encountered or fought into extinction over the centuries. Well-documented publications exist of data concerning megafauna or large animals, such as the mastodons and mammoths, who appear to have possibly survived into comparatively recent times, as was revealed by Delaware or Lenni-Lenape legends, and the apparently non-fossilized remains of such creatures, as found by both Indians and pioneers alike, at 'Big Bone Lick,' in present-day Boone County, Kentucky.
Dr. Adrienne Mayor, a Classical Folklorist & Historian, has attempted in her recent work, Fossil Legends of the First Americans (NJ: Princeton University Press., 2005), to relate such encounters or traditions as being based solely upon the discovery of the fossilized remains of now extinct creatures, whose bones stimulated the imagination of the Native-Americans to 'create' tales and myths to explain their existence.
Though the above work no doubt explains, in part, the existence of such legends, it does not negate the possibility that prehistoric animals, both known & unknown to present-day science, may have existed up into the historic period or time of European contact.
Early French explorers encountered the drawings of the Piasa, a dragon-like creature whose picture by Native-Americans once decked the bluffs that existed at Alton, Illinois, on the Illinois River, while early recorded Iroquois traditions relate that tribes' conflict with the last remnant of a large creature referred to as the 'Hairless or Naked Bear.'
Sioux Indians of the Plains, who once resided in the Ohio Valley, have preserved many accounts of the Unktehi, a mysterious 'water-monster' that occasionally ate tribesmen, while the Cherokee people, told many stories of the Uktena, a giant rattle-snake who possessed what was referred to as a 'jewel' or the 'ulun suti' in its head, a treasure which many tribal warriors attempted to possess at the risk of their own lives.
Having given a 'background' to the subject, I offer the following account, preserved in The Independent Gazetteer, or The Chronicle of Freedom, published in Philadelphia, Pennsylvania, on Saturday, June 3rd, 1786, and entitled, "Extract of a letter from an officer on the Ohio, to his parents in Windham, Connecticut," which contains the following:
A creature of the amphibious kind, by the Indians called Oquao, is not the least remarkable among the innumerable curiosities with which this country abounds. This animal has two heads; a property, which, perhaps, belongs not to any other in existence: His tail is fifteen feet long: otherwise he in some measure resembles a turtle:By day the Oquao is rarely seen, then he lies close in his retreat, under water, but in night he wanders abroad to satisfy his hunger---The deer are his favorite game: and his manner of taking them is insidious and cruel: He places himself in a deer path, where without motion, and having the appearance of a lump more than of an animal, he waits the approach of his un-suspicious prey.The deer strides heedless over his destroyer, who throws out his tail, entwines him in a moment, drags him in spite of all his resilience, to the next creek, and there drowns and devours him.
One of these uncommon animals was discovered last week by a soldier early in the morning, as he was dragging off the booty of the night: Several gentlemen who were there went immediately in quest of him; and as these creatures are far from being swift, he was soon overtaken: With great difficulty, after having borne the strokes of a dozen clubs for nearly half an hour, he was killed---happily for us he held his prey to the last, otherwise our attempt might have been attended with some danger---His eyes had such a malignant keeness, that I could not help regarding the very sight of him as being truly horrid. We released the deer, which was already dead, from his fatal gripe {grip}, brought him home, and weighed him (the Oquao) and found his weight four hundred forty-four pounds.
One can choose to believe whether the above account is fictive or based in reality. Perhaps it was an encounter with an extremely large alligator which now are not native to the Ohio Valley. The rare 'blue-eyed albino alligators' of the Southern swamps, which are occasionally encountered today, relate however that abnormalities do occur at times within the animal kingdom.
Ancient, Medieval & even frequent modern accounts of the birth of two-headed snakes, calves, turtles, and even human Siamese twins that attain maturity or adulthood, attest to the possible validity of such an account as recorded in 1786.
If nothing else, the above reveals once again the vast diversity of materials that await curious researchers, as they peruse the collections available here at The Historical Society of Pennsylvania.