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1Department of Geological Sciences, University of Florida
2Florida Museum of Natural History, University of Florida
3Department of Biological Sciences, Vanderbilt University


I. Introduction
II. Composition and Age of Peace River Basin Vertebrate Fossils
A. The Upper Peace River Fauna
B. The Lower Peace River Fauna
III. The Peace River Paleo Project
A. Research
B. Education
C. Outreach
D. Donations and Specimens needed for Study
IV. Chronology and Summary of Primary Scientific Publications on the Vertebrate Fossils of the Peace River
V. List of Donors of PRB Specimens
VI. References Cited


The Peace River Paleo Project is a multi-year effort to thoroughly study the vertebrate fossils from the Peace River and its associated tributaries. The land area drained by the Peace River and its tributaries is called the Peace River Basin (PRB) which covers about 1400 sq. miles in south-central Florida This Google Map cannot be loaded because the maps API does not appear to be loaded. The river originates in central Polk County and flows in a generally south to southwest direction for about 100 miles to its mouth in Charlotte Harbor. The vast majority of the recovered fossils are collected in either Hardee or De Soto Counties by members of the general public, not by professional paleontologists. Annually, thousands of vertebrate fossils are recovered from the PRB by many hundreds of individuals under the authorization of collecting permits issued by the State of Florida. While many of these are Floridians, others travel from across the U.S. and even from other countries to hunt for fossils in the PRB.

This project will include specimens both in museum collections, primarily acquired by donated from “amateur” collectors, and those in private collections. In addition to technical scientific publications, the outcomes of the project are expected to include a substantial amount of public outreach and support for K-12 education. Types of outreach may include, but are not limited to, internet sites, public lectures to fossil clubs, at museum events, and on the Florida Museum’s YouTube channel, identification guides, freely available 3D scans of specimens that can be 3D printed, fossil identification events, and more. We will work with K-12 educators, especially those in Hardee, De Soto, and surrounding counties to provide them with real and virtual fossils, data, and expertise that they can use to generate grade-appropriate lesson plans for the classes they teach.

Provisional project timeline:

Fall 2020 Semester: identification and curation of uncataloged PRB specimens in Florida Museum of Natural History (FLMNH) collection (MTR and RCH).

Spring 2021 Semester: scanning of specimens and dietary analysis of PRB herbivores in FLMNH collection (MTR and LRGD); measuring, imaging, and writing descriptions of FLMNH specimens (RCH and MTR); rare earth elements and strontium isotope analysis of PRB specimens (MTR and BJM).

Summer 2021 & Fall 2021 Semester 2021: measuring, scanning, imaging and writing descriptions of fossils in private collections and those donated (MTR and RCH); dietary analysis of PRB herbivores in private collections (MTR and LRGD); production of PRB content for FLMNH web site (RCH and MTR); presentation(s) at the annual meeting of the Society of Vertebrate Paleontology (or alternatively GSA); meet with regional K-12 educators.

Spring 2022 Semester: complete analyses, finish writing scientific papers, and submit for publication; presentations at the annual meeting of the Southeastern Section of the Geological Society of America; public lectures; complete identification guides for PRB fossils. (Some of these may extend into the Summer 2022 Semester.)

Composition and Age of Peace River Basin Vertebrate Fossils

Most of the vertebrate fossils from the Peace River Basin (PBR) are collected from modern sand and gravel bars on the bed of the Peace River and some of its tributary creeks. The fossils are freed by erosion from the sediments or rocks making up the bed and banks of the river, especially during floods when the river’s current is greatly increased. The fossils move downstream with sand and gravel until the current slows down to the point that they stop moving. This cycle of repeated erosion, transport downstream, and deposition results in fossil assemblages that are mixed with the bones of modern animals and man-made objects such as bottles.

More rarely, the fossils are found “in place” in the original sediment that buried them. These sites can be submerged, for example Peace River 3A, or in the dry bank, for example the Harrison Ranch locality. In a few instances, Miocene specimens have been found embedded in rocks of the Peace River Formation.

Since the pioneering works of Sellards (1915a; 1916b), it has long been recognized that the vertebrate fossils of the PBR belong to more than one geologic age. In the following discussion, fossils collected from the open pit phosphate mines in Polk and western Hardee Counties are not included; only those from the bed and banks of the Peace River and its tributaries. Using the currently accepted biochronologic ranges for vertebrate species during the Neogene and Quaternary of North America (Tedford et al., 2004; Bell et al., 2004), almost all the vertebrate fossils recovered from the PBR fall into just two time intervals, late Miocene and late Pleistocene. These specimens make up the Lower Peace River Fauna and the Upper Peace River Fauna, respectively. Early Pleistocene (Blancan) fossils have been found at a location on one of the creeks in the PBR and at least one middle Miocene specimen (UF/TRO 32000), a tooth of a merychippine equid, was collected in the Peace River near Gardner in Hardee County.

The Upper Peace River Fauna

The currently known make-up of the Upper Peace River Fauna is listed in Table 1, along with the number of assigned catalog numbers in the vertebrate paleontology collections of the Florida Museum of Natural History. These numbers provide some indication of the relative abundance of each species. However, donations for fossils of rare species are more likely than those of common ones, so numbers for rare species are likely inflated to some degree. Also, species whose individuals each have large numbers of osteoderms can have inflated numbers over those that do not. There is also a clear bias against animals with small body size in the fauna.

Table 1. Composition of the Upper Peace River Fauna. Number of specimens counts only those in the Florida Museum of Natural History vertebrate paleontology collections.

Scientific Name Common Name Status Number of Specimens
Amia calva bowfin living in Florida 1
Chelydra osceola Florida snapping turtle living in Florida 4
Kinosternon baurii striped mud turtle living in Florida 1
Sternotherus minor loggerhead musk turtle living in Florida 1
Apalone ferox Florida softshell turtle living in Florida 10
Pseudemys nelsoni Florida red-bellied cooter living in Florida 12
Pseudemys concinna river cooter living in Florida 4
Trachemys scripta red-eared slider living in Florida 90
Terrapene carolina box turtle living in Florida 4
Terrapene putnami giant box turtle extinct 24
Gopherus polyphemus gopher tortoise living in Florida 3
Hesperotestudo crassiscutata Florida giant tortoise extinct 101
Alligator mississippiensis American alligator living in Florida 21
Colubridae, gen. and sp. indet. nonvenomous snakes living in Florida 2
Crotalus adamanteus eastern diamondback rattlesnake living in Florida 1
Anatidae, gen. and sp. indet. ducks and geese living in Florida 4
Scolopacidae, gen. and sp. indet. sandpiper living in Florida 1
Meleagris gallopavo wild turkey living in Florida 4
Ardea herodias great blue heron living in Florida 1
Dasypus bellus beautiful armadillo extinct 6
Glyptotherium floridanum Florida glyptodont extinct 133
Holmesina septentrionalis giant armadillo extinct 113
Megalonyx jeffersoni Jefferson’s ground sloth extinct 1
Eremotherium laurillardi giant ground sloth extinct 2
Paramylodon harlani Harlan’s ground sloth extinct 13
Sylvilagus floridanus eastern cottontail living in Florida 2
Sylvilagus palustris marsh rabbit living in Florida 1
Sciurus niger fox squirrel living in Florida 1
Neofiber alleni round-tailed muskrat living in Florida 1
Neochoerus pinckneyi capybara extinct 25
Castoroides dilophidus giant beaver extinct 13
Canis dirus dire wolf extinct 5
Urocyon cinereoargenteus grey fox living in Florida 1
Procon lotor raccoon living in Florida 6
Tremarctos floridanus Florida short-faced bear extinct 3
Lynx rufus bobcat living in Florida 2
Panthera onca jaguar extirpated from Florida 7
Panthera atrox American lion extinct 1
Smilodon fatalis saber-tooth cat extinct 5
Pecari sp. collared peccary extirpated from Florida 2
Platygonus compressus flat-headed peccary extinct 4
Mylohyus fossilis eastern long-nosed peccary extinct 2
Palaeolama mirifica stout-legged llama extinct 19
Hemiauchenia macrocephala large-headed llama extinct 7
Bison latifrons long-horned bison extinct 78
Odocoileus virginianus white-tailed deer living in Florida 84
Tapirus veroensis Vero tapir extinct 36
Equus ferus fraternus New World horse extinct 419
Mammuthus columbi Columbian mammoth extinct 52
Mammut americanum American mastodon extinct 22
Trichechus manatus West Indian manatee living in Florida 1


The Upper Peace River Fauna clearly belongs to the Rancholabrean Land Mammal Age based on the presence of Bison, as the occurrence of that genus in North American fossil sites south of latitude defines that age (Bell et al., 2004). Other species in the fauna that are characteristic of the Rancholabrean include Glyptotherium floridanum, Neofiber alleni, Canis dirus, Urocyon cinereoargenteus, Tremarctos floridanus, Panthera onca, Panthera atrox, and Smilodon fatalis. Two extinct species of Bison are known from the Pleistocene of Florida, Bison latifrons and Bison antiquus. Robertson (1974) proposed that in Florida Bison latifrons was restricted to the early Rancholabrean and Bison antiquus to the late Rancholabrean, and this conclusion was followed by most subsequent researchers. But it is now known that Bison latifrons persisted into the late Rancholabrean in the southeastern United States (Patterson et al., 2012). The two species of Bison co-existed in Florida during the late Rancholabrean, although they have not been recorded together at the same locality and thus may have lived in different habitats. The single Bison horn core from the PBR (UF 266254) belongs to Bison latifrons. For that reason, all the PBR fossils of Bison are listed in the table as that species, although it is possible that some may represent Bison antiquus.

The Lower Peace River Fauna

The Lower Peace River Fauna consists of vertebrate fossils from the PRB that are either collected directly from exposures of the Peace River Formation (sensu Scott, 1988) or, more commonly, from Pleistocene or Holocene alluvial sediments that contain of reworked sediments and fossils from the Peace River Formation. Overall, the Peace River Formation ranges in age from middle Miocene to earliest Pliocene (Scott, 1988; Missimer, 2002). Deposition was not continuous through this interval, as evidenced by wide-spread unconformities. Missimer’s (2002) analysis of sediments and fossils found in the Peace River Formation in Charlotte and Lee Counties demonstrated the presence of numerous coastal and near shore marine environments to a maximum water depth of 20 m (65 ft.).

The most commonly recovered fossils of the Lower Peace River Formation are shark teeth; teeth, dermal “thorns,” and tail spines of rays; and robust elements of nearshore marine bony fish. While the shark teeth are among the most sought after specimens by avocational and recreational collectors, especially those of the larger species, they have never been the subject of a scientific publication. The species listed in Table 2 are based on preliminary identifications and a subject to change as studies progress.

Fossils of marine mammals of this fauna are also fairly common, especially broken pieces of dugong ribs. A small number of whale skulls and mandibles have been collected directly from the Peace River Formation in the bed or lower banks of the Peace River. More fragmentary fossils of whales and dolphins, usually durable teeth or bones such as the auditor bulla and petrosal are found in the river gravel beds. The most common of these are from the genus Pomatodelphis, a dolphin with a very long and narrow rostrum, ear bones of cetotheres, and sperm whale teeth. In Morgan’s (1994) review of Florida marine mammals, this assemblage was characteristic of the middle to early late Miocene. According to Morgan (1994), marine mammals of the late Miocene to early Pliocene in Florida consist of an entirely different array of cetaceans and dugongs along with the addition of phocid seals and the walrus Ontocetus (formerly Trichecodon). None of the cetaceans and dugongs from this assemblage have as yet been collected from the PBR, which suggests that the age of most of the Peace River Formation exposed in the region is early late Miocene (or older). This would correspond to the Tortonian Stage of the geologic time scale, which corresponds to the Clarendonian and early Hemphillian North American Land Mammals Ages.

Fossils of land mammals are rare in the Lower Peace River Fauna, as would be expected from the marine nature of the Peace River Formation in the area. They are much rarer than what is found in the phosphate mines of western Polk and Hardee Counties and eastern Hillsborough and Manatee Counties, which have produced large numbers and diverse faunas of land mammals and reptiles ranging in age from middle Miocene to earliest Pliocene (Sellards, 1915a; 1916b; Simpson, 1930a; Webb and Hulbert, 1986; Webb et al., 2008). All known fossils of land mammals in the Lower Peace River Fauna are isolated and frequently waterworn. Isolated teeth are the most commonly found element, although some postcranial bones are known, including a toe bone from a three-toed horse described in Leidy (1889b). Given the proximity of the Peace River and some of its tributaries to the phosphate mines, it is surprising that none of the recovered PBR specimens belong to species from the latest Hemphillian Palmetto Fauna, which is the most widespread and common terrestrial vertebrate assemblage in the phosphate mines (Webb et al., 2008). Instead they belong to species from the Archer Fauna from north-central Florida of Webb and Hulbert (1986), which ranged from the late Clarendonian to early Hemphillian. This assemblage of species has also been found in what is considered to be a freshwater stream deposit in Nichols Mine in western Polk County.

Therefore, the biochronology of the marine and land mammals of the Lower Peace River Fauna are in agreement that its predominate age is early late Miocene (Tortonian). It is very likely that limited exposures of the Peace River Formation in the PBR are either younger (e.g., Zanclean) or older (middle Miocene) than the Tortonian. This would explain the very rare occurrence of vertebrate fossils from those time intervals in the PBR. Examples are a femur of the seal Callophoca and a tooth a merychippine grade horse, which are mostly likely younger and older than typical members of the fauna, respectively.

Table 2. Composition of the Lower Peace River Fauna. Number of specimens counts only those in the Florida Museum of Natural History vertebrate paleontology collections.

Scientific Name Common Name Number of Specimens
Carcharhinus sp. or spp. requiem sharks 81
Carcharhinus leucas bull shark 2
Negaprion sp. lemon shark 78
Galeocerdo aduncus extinct tiger shark 3
Galeocerdo cuvieri tiger shark 19
Physogaleus contortus extinct tiger shark 4
Hemipristis serra extinct snaggle-toothed shark 65
Sphyrna sp. hammerhead shark 1
Carcharocles megalodon megalodon 43
Carcharodon hastalis extinct great white 7
Isurus oxyrinchus shortfin mako 2
Carcharias taurus sand tiger shark 5
Squatina sp. angel shark 1
cf. Myliobatis sp. or spp. eagle rays 4
Aetomyaeus sp. eagle ray 1
Aetobatus narinari spotted eagle ray 5
Chaetodipterus sp. spadefish 1
Pogonias sp. black drum 1
Pagrus sp. seabream 4
Diodontidae burr and porcupine fish 7
Psephophorus sp. leatherback sea turtle 1
Metaxytherium floridanum dugong 7
Parietobalaena sp. extinct baleen whale 2
Cetotheriidae extinct small baleen whales 3
Physeteridae sperm whales 2
Choneziphius trachops extinct beaked whale 1
Pomatodelphis inaequalis long-snouted dolphin 3
Pomatodelphis bobengi long-snouted dolphin 1
Callophoca sp. extinct seal 1
Aepycamelus major giraffe-camel 1
Synthetoceras sp. “slingshot” artiodactyl 1
Teleoceras fossiger stout-limbed rhino 1
Cormohipparion ingenuum three-toed horse 14
Cormohipparion plicatile three-toed horse 6
Nannippus westoni three-toed horse 3
Nannippus morgani three-toed horse 1
Pseudhipparion skinneri three-toed horse 15
Neohipparion trampasense three-toed horse 2
Calippus elachistus three-toed horse 1
Calippus hondurensis three-toed horse 1
merychippine-grade equid three-toed horse 1

Peace River Paleo Project: Research

We currently plan to complete and publish three studies as part of the PRiPP. All will be published in peer-reviewed, open access journals. We will seek collaborators with special expertise for each study.

  1.  Descriptive review of the Upper Peace River Fauna (Pleistocene-aged vertebrates).
  2. Descriptive review of the Lower Peace River Fauna (Miocene-aged vertebrates).
  3. Multi-proxy analysis of the diet and paleoecology of Upper Peace River Fauna herbivores.

Combined, the two description papers will be the first comprehensive review of Peace River fossils in 130 years.

Donations of additional specimens from the PRB are not necessary to complete the two descriptive studies, but will be welcomed, especially those that add additional species to one of the faunas or that add to our understanding of a particular species. Those who own particularly complete or rare PRB that they do wish donate can still contribute to this project! See the Lists of known species for each fauna are listed above in Tables 1 and 2.

Multi-proxy analysis of the diet and paleoecology of Upper Peace River Fauna herbivores

We will conduct the first such analysis of Peace River mammalian herbivores using the following techniques: stable carbon and oxygen isotopes, microwear, and mesowear. The combination these methods should provide a robust interpretation of the diets of the species under study, and allow us to make inferences about regional ecology and habitats.

Stable carbon and oxygen isotopes derived from tooth enamel (or dentine in case of sloths). Carbon isotopes reveal the relative amounts of plants eaten during the time of tooth mineralization that used C3 photosynthesis (primarily bushes, shrubs, and trees) versus C4 photosynthesis (primarily grasses). Oxygen isotopes reveal information on temperature and precipitation. This method requires destructive sampling of a small portion of the tooth to acquire enamel. To ensure that only adult teeth are sampled, only third molars will be used, except for mammoths and mastodons for which second or third molars can be used. Teeth do not need to be complete for this method, but must preserve sufficient enamel.

Microwear analysis looks at microscopic wear features (pits and scratches) created when an animal chews its food. Size, frequency, and allignment of pits and scratches can distinguish between grazers, browsers, and fruit/seed eaters. Only features formed during last two weeks of life are preserved. Only upper molars will be used in this analysis. Teeth must be very well preserved, so that wear features are preserved and not eroded or worn off. In general, if the roots of isolated teeth are missing, The analysis is done on casts, so that specimens to do not need to be donated to be included in this study, except for deer, bison, and horse teeth which have to be subjected to destructive sampling for rare earth elements.

Mesowear analysis looks at the shape of the occlusal surface of worn teeth in profile. Animals eating low-lying plants with relatively large amounts of dust and grit on them wear their molar teeth flat. Animals eating softer leaves higher off the ground retain occlusal surfaces with ridges and valleys until old age. Only upper molars will be used and must preserve the entire buccal (outer) half of the occlusal surface. Teeth must be well preserved, with no or only minor waterwear. This analysis can be done by quick visual inspection of the tooth and digital images. Specimens do not need to be donated to be included in this study, except for deer, bison, and horse teeth which have to be subjected to destructive sampling for rare earth elements.

Peace River Paleo Project: K-12 Education

Three Major Goals:

  1. Fossil Kits with Peace River Fossils for use in K-12 Classrooms
  2. Specimens to be scanned and uploaded to open-access platforms for 3D printing in the classroom and beyond (fossil clubs, science clubs, science camps, even at home!)
  3. Collaborate with K-12 teachers (especially in Hardee and DeSoto counties) to create paleontology-oriented lesson plans:
    • Measuring fossil teeth (e.g., shark teeth, horse teeth) to study evolution & body size.
    • Osteometry of alligator, turtle, & tortoise limb bones (e.g., femur : tibia)
    • Mesowear lesson plan
    • What the teachers’ come up with!

Peace River Paleo Project: Outreach

Main goals include:

  1. Adding photo and/or scanned images of PRB specimens to online collection database.
  2. Add 20-25 species accounts to FLMNH web page (e.g., Bison latifrons, Panthera atrox, Hesperotestudo crassiscutata, Galeocerdo aduncus).
  3. Utilizing social media to create online identification guides for Peace River fossils.
  4. ID fossils in personal collections at home visits by museum staff and students.
  5. Organizing virtual events with fossil clubs to determine what you would like to gain from this project!
  6. Arranging ADA compliant Peace River field visits for disabled science enthusiasts

Peace River Paleo Project: Donations and Specimens Needed for Study

For the description studies we will gladly accept donations of any PRB specimens, but in particular are in need of specimens that either belong to species not listed above in Tables 1 and 2, or for which we have four or fewer specimens. We can also accept donations of vertebrate fossils from the PRB of lesser quality for school kits and teachers.

In cases where there is a scientifically valuable specimen from the PRB which the owner does not want to donate, we can scan the specimen to create a 3D virtual copy that can be studied and also used for educational purposes. Owners of such specimens should contact

For the dietary and paleoecology project we are need of the following numbers of specimens:

Species stable isotopes microwear mesowear
Tapirus veroensis 6-8 20 20
Odocoileus virginianus* 10 15 20
Bison sp.* 6-8 15 15
Palaeolama mirifica 15 20 20
Hemiauchenia macrocephala 15 20 20
Platygonus compressus 15 20 —–
Mylohyus fossilis 15 20 —–
Mammuthus columbi 5 10 15
Mammut americanum 15 15 —–
Paramylodon harlani 12 15 —–

Note that some specimens potentially could be used in two or even all three analyses if they meet the required criteria. An ‘*’ after a species name means that specimens must be destructively sampled for REE to ensure they are fossil and not modern. Otherwise, specimens for microwear and mesowear do not require donation.

Chronology and Summary of Primary Scientific Publications on
the Vertebrate Fossils of the Peace River

List of Donors of PRB Fossils

Juanita K. Akin

Adam Black

John J. Boyce

Robin Brown

Taylor Burnham

Kent R. Carlson

Joel Carr

Heinz-Hubert Cloeren

R. Davis

Edward DeRouin

Joseph R. Dumont

Frank A. Garcia

Tricia Glotfelty

A. Gricius

Grant Groves

William T. Harrison Jr.

David P. Hoffman

Mitchell E. Hope

Christine Horning

James R. Huntoon

Steve Hutchens

Hänsel I. Jacob

Rhada G. Jones

Nicholas Kamboures

Eric Kendrew

James B. Kendrick

Andreas Kerner

J. Kurtzman

Jay Lev

Kenneth W. Marks

Fred Mazza

John J. Miller

David Mitchell

Alice Morales

H. R. Parkhill

Roger W. Portell

Jim Ranson

Ken T. Reems

John A. Reynolds

Dick and Anne Rosecrans

S. Schaefer

Michael and Seina Searle

Robert Sinibaldi

E. Sockolosky

R. Sprowl

Louis G. Stieffel

George Sunberg

Barbara Toomey

University of Wisconsin-Milwaukee, Department of Geosciences

Thompson H. van Hyning

John S. Waldrop

James A. Walters

Phillip M. Whisler

Steven Wilson

Douglas B. Wright

Marcia Wright

D. Wyndham

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Hulbert Jr., R. C., G. S. Morgan, and A. Kerner. 2009. Collared peccary (Mammalia, Artiodactyla, Tayassuidae, Pecari) from the late Pleistocene of Florida; pp. 543–555 in L. B. Albright III (ed.), Papers on Geology, Vertebrate Paleontology, and Biostratigraphy in Honor of Michael O. Woodburne. Museum of Northern Arizona Bulletin 65. Flagstaff, Arizona.

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Leidy, J. 1889b. Description of vertebrate remains from Peace Creek, Florida. Transactions of the Wagner Free Institute of Science of Philadelphia 2:19–31.

Leidy, J. 1890. Hippotherium and Rhinoceros from Florida. Proceedings of the Academy of Natural Sciences of Philadelphia 42:182–183.

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Patterson, D. B., A. J. Mead, and R. A. Bahn. 2012. New skeletal remains of Mammuthus columbi from Glynn County, Georgia with notes on their historical and paleoecological significance. Southeastern Naturalist 11(2):163–172.

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Sellards, E. H. 1915b. Chlamytherium septentrionalis, an edentate from the Pleistocene of Florida. American Journal of Science 40:139–145.

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