BIMONTHLY BULLETIN of the CAYMAN ISLANDS DEPARTMENT of ENVIRONMENT ‘S TERRESTRIAL RESOURCES UNIT FOSSIL VERTEBRATES FROM THE CAYMAN ISLANDS By: Gary Morgan, New Mexico Museum of Natural History The Cayman Islands are a hot spot for The first person to discover vertebrate paleontology. Specifically, the Caymans fossils in the Cayman Islands was Lord are known for vertebrate fossils, Moyne, who found fossils of a large including crocodiles, birds, and rodent in a cave at Stake Bay on Cayman mammals, dating to about the last Brac in 1937. The next year, Bernard 15,000 years, or the Pleistocene (also Lewis from the Institute of Jamaica, a known as the Ice Age) and Holocene member of the legendary Oxford epochs in geological terms. Fossils have University Biological Expedition to the been found in two types of deposits in Cayman Islands, collected additional the Caymans; loose sediments in caves fossils of a large rodent in a cave on on Cayman Brac and Grand Cayman and Cayman Brac. In 1964, Thomas Patton mangrove peat deposits and “cow from the Florida State Museum (now wells” on Grand Cayman. Only a few the Florida Museum of Natural History) fossils have been recovered from small at the University of Florida explored caves on Little Cayman. Cayman Brac in search of fossil vertebrates. The author (left) and Greg McDonald (right) excavate fossils from a cave on Grand Cayman in 1976. Flicker Bulletin # 29 – FEB / MAR 2017 He discovered large samples of fossil Until the late 1970s, all vertebrate reptiles, birds, and mammals in two fossils from the Cayman Islands had caves on Cayman Brac, since named been recovered from caves on Cayman Patton’s Fissure and Pollard Bay Cave. Brac and Grand Cayman. That changed dramatically with two important As a beginning graduate student at the discoveries on Grand Cayman. In 1979, University of Florida (UF) in 1975, I was Edward and Robert Materne found a recruited by Patton to study the fossil large number of darkly stained bones vertebrates from the Cayman Islands for protruding from piles of organic my Masters Thesis. Having grown up in sediment (peat) excavated from a a small town in Ohio, I was thrilled with mosquito control canal in a mangrove the opportunity to do field work and swamp north of George Town. Later research on a tropical island group in that same year, the Maternes took the Caribbean. My first field trip to the those bones to the U. S. National Cayman Islands was in 1976, with fellow Museum of Natural History, part of the UF students Greg McDonald and Nina Smithsonian Institution in Washington, Thanz, which began a 20 year DC, where I was working at the time. paleontological odyssey that included Much to my surprise, almost their entire four more trips to the Caymans to sample of fossils belonged to crocodiles, collect fossils in 1979, 1980, 1986, and including a nearly complete skull –see 1993. below. Fossil skull of the Cuban crocodile (Crocodylus rhombifer) from the Crocodile Canal site, Grand Cayman. Dorsal (top) view on left, ventral (bottom) view on right. Flicker Bulletin # 29 – FEB / MAR 2017 This site has since been named the The Ice Age fossil vertebrates from the Crocodile Canal. Also in the late 1970s, Cayman Islands represent an interesting Grand Cayman residents Rolin Chisholm mix of species that still occur in the and Ira Thompson collected a second islands, including frogs, lizards, snakes, large sample of crocodile bones, from birds, and bats, together with crocodiles dark organic sediments removed from a and numerous species of birds and cow well on Chisholm’s property near mammals no longer found in the North Side (see below). Cow wells are Caymans. Some of these species are small, water-filled depressions in the completely extinct, while others are limestone that often contain peat locally extinct in the Cayman Islands but deposits and fossils, primarily still live elsewhere in the West Indies, crocodiles. primarily in Cuba or Jamaica. Over the next two decades, several Crocodiles are the largest fossil additional samples of crocodile fossils vertebrates recovered from the Cayman were found on Grand Cayman, including Islands. Study of the cranial anatomy of a water-filled cave in a banana about a half dozen crocodile skulls from plantation at Furtherland Farms in 1986 Grand Cayman (see photos) reveals that and a cow well on the grounds of the they belong to the rare Cuban crocodile Queen Elizabeth II Botanic Park in 1993. (Crocodylus rhombifer), rather than the more The author (left) and Rolin Chisholm (right) collect fossils of the Cuban crocodile from a cow well on Grand Cayman in 1986. Flicker Bulletin # 29 – FEB / MAR 2017 more common and widespread The Spanish word caimán (from the American crocodile (Crocodylus acutus). Carib cayman) is the name used for tropical American crocodiles. The Cuban crocodiles are now restricted to Spanish name for the island group is several freshwater swamps in Cuba, Islas Caimán, the “Crocodile Islands.” although the fossil record reveals that The resident population of crocodiles this crocodile was considerably more disappeared from Grand Cayman in the widespread in the past, with locally 1800s, probably resulting from extinct populations on Grand Cayman, overhunting. many islands in the Bahamas, and the Dominican Republic. The Cuban Fossil birds from the Cayman Islands crocodile is one of the most terrestrial include four extinct species and seven of all living crocodilian species, and is species now absent from the Caymans known to prey on large rodents called but still found on other islands in the hutias that are known as fossils from the West Indies. Bones of an eagle-sized Cayman Islands (see below). raptor (Titanohierax gloveralleni) were found in a small cave near East End on Grand Cayman. The past presence of crocodiles on Grand Cayman was mentioned in several historical documents, including a book about Sir Francis Drake’s visit to Grand Cayman in 1586 and references by Captain William Jackson in 1642 and Edward Long in 1774. The name of the Cayman Islands was almost certainly derived from the former abundance of crocodiles on Grand Cayman. Top right: Fossil skull of the extinct rodent or hutia (Capromys) from Cayman Brac, on the right is a photo of the Cuban hutia (Capromys pilorides) (Photo by Nancy Albury). Below: Jaws and teeth of hutias from a cow well on the grounds of the Botanic Park. These fossils are strongly corroded because they were eaten and digested by a crocodile. Flicker Bulletin # 29 – FEB / MAR 2017 This large bird is also known from fossil The fourth extinct bird from the deposits in Cuba, Hispaniola, and the Caymans, a large snipe (Capella) found Bahamas. Titanohierax was a gigantic in two caves on Cayman Brac, is also Antillean hawk related to the great black known from fossil cave deposits in the hawk (Buteogallus urubitinga) from the Bahamas. Birds identified as fossils from tropics of Central and South America. It Grand Cayman or Cayman Brac but now probably fed on several species of large locally extinct in the Caymans include: rodents that are also now extinct in the Audubon’s shearwater (Puffinus Caymans. lherminieri), plain pigeon (Columba inornata), Key West quail dove Another large predatory bird, an extinct (Geotrygon chrysia), great lizard cuckoo caracara (Caracara creightoni), was (Saurothera merlini), burrowing owl identified from a cave on Grand (Athene cunicularia), and Cuban crow Cayman, and is also known by fossils (Corvus nasicus). This latter group from the Bahamas. An extinct species of includes one additional bird that is of bullfinch (Melopyrrha latirostris) was exceptional interest, a hummingbird! described from a cave on Cayman Brac. This extinct bullfinch is much larger than Fossils of a tiny bird from a cave on the the similar Cuban bullfinch (Melopyrrha north coast of Grand Cayman are very nigra) that still lives on Grand Cayman similar to bones of the Cuban emerald and Cuba (see photos). (Chlorostilbon ricordii), a hummingbird now found in Cuba and the Bahamas (see the front cover). The Caymans are one of the only island groups in the West Indies that lack hummingbirds in the modern fauna. We now know they inhabited Grand Cayman in the recent past but went extinct here for some unknown reason. The living mammal fauna of the Cayman Islands consists entirely of bats, including eight species. Fossils from the Cayman Islands add five extinct species of terrestrial or non-volant mammals (i.e., not bats), as well as five additional species of bats now locally extinct in the Caymans. There are two new species of the small, shrew-like insectivore Top row, left: fossil beak of an extinct Nesophontes, one each from Cayman species of bullfinch (Melopyrrha Brac and Grand Cayman. Nesophontes is latirostris) from Cayman Brac; also known from fossil deposits in Cuba, right: skull of a modern Cuban bullfinch Hispaniola, and Puerto Rico. (Melopyrrha nigra) from Cuba. Bottom: stamp from the Cayman Islands with the Cuban bullfinch. Flicker Bulletin # 29 – FEB / MAR 2017 It is an extinct genus distantly related to Within the past few years, several new the larger insectivore Solenodon that fossil finds have been made in the still lives in Cuba and Hispaniola. Fossils Cayman Islands. Caymanian residents from Grand Cayman, Cayman Brac, and have collected half a dozen fossil skulls Little Cayman represent several extinct of hutias, including both Capromys and species of large rodents the size of a Geocapromys, as well as crocodile skulls house cat, called hutias or coneys, and Pat Shipman and Alan Walker found referred to the genera Capromys and fossils of Capromys in a cave on Little Geocapromys. The larger of these two Cayman. Undoubtedly, new discoveries rodents, Capromys, has a longer tail and of fossil vertebrates remain to be made is primarily arboreal, while the smaller in the Cayman Islands.