Monkey Jungle Hammock 1

University of Florida Vertebrate Fossil Locality DA002

Location

The site is located within the boundaries of the Monkey Jungle zoological park in the southern Miami metropolitan area, Dade County, Florida. 25.57º N; 80.43º W.

Age

• Late Pleistocene Epoch; late Rancholabrean land mammal age
• 20,000-15,000 years ago

Basis of Age

The co-occurrence of Panthera atrox, Puma concolor, Sigmodon hispidus, Neotoma floridana, Oryzomys palustris, and Neofiber alleni indicated a late Rancholabrean age in the chronologic sequence of Florida’s Pleistocene faunas (Morgan and Hulbert, 1996). The bones were leached of collagen and so could not be radiocarbon dated. The presence of cave-dwelling bats indicated the site dates to a time of much lower global sea levels, producing dry caves for these species to inhabit (Morgan, 1991). This combination suggests deposition during the last glacial maximum, about 20,000 to 15,000 years ago.

Geology

A unconsolidated mix of organic material and fine-grained calcareous sand (Ober, 1978).

Depositional Environment

A dry sinkhole. Bone accumulation by a combination of deadfall trap and mammalian and avian predators.

Fossils

Over 850 identifiable vertebrate fossils were recovered, most belonging to small species, such as the shrew Cryptotis parva and the flying squirrel Glaucomys volans. Bones and teeth of eight different species of bats were present, making it one of the most diverse assemblages of bats known from a Pleistocene site in North America. Many of the amphibian and small reptile fossils remain unidentified, so faunal richness is expected to greatly increase once they are studied. Most of the fossils are fragmentary, isolated elements; no associated skeletons were found.

Excavation History and Methods

Lewis Ober and William Weaver of Miami Dade College noticed fossil bones weathering out of sediment that had been excavated out of sinkhole to form an alligator habitat at the Monkey Jungle zoological park. No in situ sediment was available for excavation. They had all available sediment from the sinkhole moved by truck to a safe location on the part where it was wet screened (through ½ inch hardware cloth and window screen). The residue on the smaller screen was then soaked in water which allowed organic material to float to the top and be removed. Although the bulk of the specimens are clearly Pleistocene fossils, a few modern animal bones were also found. Presumably they derived from near the top of the sinkhole deposit, prior to its excavation. All specimens were collected in 1969 or 1970.

Discussion

The fossil locality usually referred to in the scientific literature as Monkey Jungle Hammock, or simply Monkey Jungle, is here called Monkey Jungle Hammock 1. This emphasizes its different age and fauna from a second fossil locality found on the park, Monkey Jungle Hammock 2 (Morgan, 1991). Monkey Jungle Hammock 1 is notable for its far southern location; it is one of the southernmost Pleistocene faunas in the United States. Like the nearby Cutler Hammock locality excavated in the late 1980s, many of the specimens from Monkey Jungle Hammock 1 are the remnants of prey of mammalian or avian predators (Morgan 2002).

The fossil bat assemblage from Monkey Jungle Hammock 1 is probably its most important scientific aspect. They have been studied by Martin (1977) and Morgan (1991, 2002). Eumops floridanus, a bat, is a species described as a fossil from the Melbourne site but later recognized as still living in southern Florida (Timm and Genoways, 2004). This is one of only two Pleistocene records for this species. Morgan (1991) tentatively identified an extinct species of bat, Pteronotus pristinus, at Monkey Jungle Hammock 1. This species was first found in Cuba. If correctly identified, it represents a rare dispersal event from Cuba to Florida. Another species, Mormoops megalophylla, is only known from two other Pleistocene localities in Florida. Today this species is widespread in the Caribbean and Neotropics but no longer inhabits Florida. Three of the bats from Monkey Jungle Hammock are obligate cave-dwellers, but there are no dry caves today in South Florida because high water tables fill them with water. These cave-dwelling bats are evidence of dry cave habitats during the late Pleistocene of South Florida (Morgan, 1991, 2002).

Another notable feature of the Monkey Jungle Hammock 1 fauna is the great diversity of mammalian carnivores based on very few specimens. There are four species of cats, three canids, a bear, skunk, and raccoon. The absence of sloths, proboscideans, and bison is most likely a reflection of a bias against very large specimens in how the site formed. All are present at the nearby Cutler Hammock site.

Sources

• Original Author: Richard C. Hulbert Jr.
• Original Completion Date: March 11, 2015
• Editor(s) Name(s): Natali Valdes
• Last Updated: February 17, 2022

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