Agricola Road Site
University of Florida Vertebrate Fossil Locality PO047
The site was located about 3.5 miles (5.6 km) east of Bradley, Polk County, Florida, in the Hookers Prairie Mine. It gets its name due to its proximity to Agricola Road. It was exposed by commercial phosphate mining. 27.80º N; 81.92º W.
- Middle Miocene Epoch; middle Clarendonian (Clarendonian 2) land mammal age
- 12-11 million years ago
Basis of Age
The Agricola Road Site produced two species of carnivores whose first appearance is diagnostic for the Clarendonian 2 interval, Albanosmilus whitfordi (formerly Barbourofelis whitfordi) and Aelurodon taxoides (Tedford et al., 2004). This agrees with the diverse assemblage of horses which correlate very well with those from well-known Clarendonian 2 faunas: Lapara Creek of coastal Texas, Minnechaduza of Nebraska, and Clarendon of the Texas Panhandle (the namesake for this land mammal age) (Hulbert, 1988a; 1988b).
The fossils derived from a lens of phosphatic clay and sand about 2 feet (70 cm) thick. Phosphate grains were white to pale gray in color, ranging in size from about 1 mm to 2 cm. While some of this lens was dug away by mining activities, an area of about 5 by 5 m remained in situ for paleontological excavation. Fossils were also recovered from nearby spoil piles.
There are about 1500 identifiable specimens from the Agricola Road Site housed in the Florida Museum of Natural History collections, of which about 1000 are cataloged. The Agricola Road Site is the best known example of a concentrated, in situ vertebrate assemblage belonging to the middle Miocene Agricola Fauna. All specimens found are isolated; most commonly teeth and partial limb bones and vertebrae. Complete bones are rare and typically only small compact bones such as carpals, tarsals, and phalanges. No skulls or complete jaws were found. Small- to medium-sized shark teeth were the most abundant fossils. Compared to other in situ Bone Valley Formation faunas, bony fish were relatively rare. No small terrestrial vertebrates were recovered by screenwashing. Within the nonmarine component of the fauna, freshwater turtles and alligator are relatively common, while the most abundant terrestrial group is the horses represented by at least seven species.
Sharks and Rays (Chondrichthyes)
Bony Fish (Osteichthyes)
Ariidae or Bagridae
†Hypohippus sp. cf. H. affinis
†Calippus n. sp.
†Nanippus n. sp.
†Gomphotherium sp. cf. G. productum
Excavation History and Methods
Fossils were first found by a commercial fossil collectors in 1986, who recognized the significance of an in situ location in the Bone Valley Formation and informed the Florida State Museum. Museum field crews lead by Gary Morgan collected the site in 1987 after receiving permission from mine operators. Overburden was washed away using water hoses and a pump. The in situ fossil-bearing layer was excavated with small hand tools and matrix was saved for screenwashing. The distinctive color of this layer made it easy to recognize in nearby spoil piles, which were also prospected for fossils. The area was later reclaimed and the site is no longer accessible.
The borophagine canid from the Agricola Road Site was referred to Aelurodon taxoides by Wang et al. (1999), although they noted that the few specimens were relatively small for this species. The small sabertoothed predator Albanosmilus whitfordi is represented by a single specimen, a partial upper canine that preserves only the root and the base of the crown. This is one of only a very few records of this species in Florida. Also rare in Florida by the middle Miocene is the horse subfamily Anchitheriinae, the large browsing horses. A single lower tooth of Hypohippus was found at the Agricola Road Site. The most common horses were all hipparions, Cormohipparion ingenuum, Pseudhipparion curtivallum, and an undescribed species of Nannippus. As middle Miocene vertebrate fossils sites are uncommon in Florida, even relatively modest sites such as this take on greater significance.
- Original Author: Richard C. Hulbert Jr.
- Original Completion Date: March 18, 2015
- Editor(s) Name(s): Natali Valdes
- Last Updated: June 16, 2015
Hulbert Jr., R. C. 1988. Calippus and Protohippus (Mammalia, Perissodactyla, Equidae) from the Miocene (Barstovian-early Hemphillian) of the Gulf Coastal Plain. Bulletin of the Florida State Museum 32:221-340.
Hulbert Jr., R. C. 1988. Cormohipparion and Hipparion (Mammalia, Perissodactyla, Equidae) from the Late Neogene of Florida. Bulletin of the Florida State Museum 33:229-338.
Hulbert Jr., R. C. 1993. Late Miocene Nannippus (Mammalia, Perissodactyla) from Florida, with a description of the smallest hipparionine horse. Journal of Vertebrate Paleontology 13:350–366.
Morgan, G. S. 1994. Miocene and Pliocene marine mammal faunas from the Bone Valley Formation of Central Florida. Pp. 239-268 in A. Berta and T. A. Deméré (eds.), Contributions in Marine Mammal Paleontology Honoring Frank C. Whitmore, Jr. San Diego Natural History Society, San Diego.
Robles, J. M., D. M. Alba, J. Fortuny, S. De Esteban-Trivigno, C. Rotgers, J. Balaguer, R. Carmona, J. Galindo, S. Almécija, J. V. Bertó, and S. Moyà-Solà. 2013: New craniodental remains of the barbourofelid Albanosmilus jourdani (Filhol, ) from the Miocene of the Vallès-Penedès Basin (NE Iberian Peninsula) and the phylogeny of the Barbourofelini. Journal of Systematic Palaeontology 11(8): 993-1022.
Tedford, R. H., L. B. Albright, III, A. D. Barnosky, I. Ferrusquıa-Villafranca, R. M. Hunt, Jr., J. E. Storer, C. C. Swisher, III, M. R. Voorhies, S. D. Webb, and D. P. Whistler. 2004. Mammalian biochronology of the Arikareean through Hemphillian interval (Late Oligocene through Early Pliocene epochs). Pp. 169–231 in M. O. Woodburne (ed.), Late Cretaceous and Cenozoic mammals of North America: biostratigraphy and geochronology,. New York: Columbia University Press.
Wang, X., R. H. Tedford, and B. E. Taylor. 1999. Phylogenetic systematics of the Borophaginae (Carnivora: Canidae). Bulletin of the American Museum of Natural History 243:1-391.
This material is based upon work supported by the National Science Foundation under Grant Number CSBR 1203222, Jonathan Bloch, Principal Investigator. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.