The vertebrate fossil record - indiana.edug404/Lectures/Lecture 16 - Vertebrate fossils and... ·...

Department of Geological Sciences | Indiana University (c) 2011, P. David Polly

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Hyena transporting head and neck of a dead bovid.

Reading: Benton Chapter 2

Environments, depositional settings and taphonomy

The vertebrate fossil record


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Bear metacarpals with stone tool cutmarks from Gravesend, United Kindom, 325,000 years old. Specimen in The Natural

History Museum, London (photo by David Polly)

What is a fossil?Preserved remains of a living organism, including its traces

Vertebrate fossils include:

1. Bones and teeth;

2. Tracks, traces, and impressions;

3. Carbonized impressions;

4. Endocasts (casts of the interior of bones, especially the cranial cavity);

5. Frozen or mummified soft tissues;

6. Molecules, including DNA, collagen, other proteins, protein fragments.


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Diagram of microscopic structure of bone (from Marieb and Mallet, Human Anatomy)

Types of ‘fossilization’Permineralization - addition of new minerals from groundwater into spaces in the bone or tooth, notably silica, calcium carbonate, iron and sulfides (pyritization), and rare earth elements

Replacement and recrystalization - removal or alteration of the original mineral and/or organic material, often happens in conjunction with permineralization

Adpression (Carbonization) - compression of quickly buried remains can cause diagenetic alteration of the entire body, leaving a carbonaceous film made up of original material and showing soft structures like organs, hair, and feathers

Impressions, casts, molds, tracks - impressions made in soft sediments by bones or tissues. Molds are “negative” impressions left by the structure, casts are fillings of molds (endocasts are fillings of the cranial cavity which produces a “cast” of the brain

Composition of boneBundled collagen (protein) fibers supporting hydroxy apatite crystals (mineral) with spaces containing cells and blood vessels

Freezing and desiccation - freezing and drying of animals can preserve both bone and soft tissues, containing everything from stomach contents to hair to DNA. Ten million mammoth carcasses are estimated to still be frozen in Siberia.

Molecules - DNA and other molecules may be preserved in fossils or sediments. Fragments of DNA can sometimes be extracted from bones and teeth less than 50,000 years old, amplified, and reassembled. Collagen fibers can be present in bone tens of millions of years old.

Amber - whole organisms encased in plant ‘sap’


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Massilamys , a rodent from Messel. Specimen from Senckenberg Museum

Compressed, carbonized fossil rodent from Messel Oil-shale Pit in GermanyMessel oil shales preserve many mammals and plants from the Geiseltalian mammal age

Fossils are compressed between shale layers, high in organic content

carbonized impressions of hair, skin, and organs are often preserved

Eocene in age - 48 million years ago


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Frozen baby mammoth from Yamal (photo from Lister and Bahn, 2007, Mammoths)

Frozen baby mammothDiscovered in 2007, one of the most complete carcasses of an extinct mammal ever discovered

Found by Yuri Khudi, nomadic reindeer tribesman from Siberia

Less than a year old, female, most hair lost but the rest of the body is intact

Pleistocene - 40,000 years old


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Taphonomy

Taphonomy - study of the processes by which animals are preserved in the fossil record, including potential biases introduced by these processes

Mortality - the causes and modes of death of the organisms

Transport - the disaggregation, dispersal, and movement of bones and teeth between the time of death and the time they are buried. Transport is most often by animals or flowing water.

Abrasion - the wear and tear on the remains during transport

Weathering - changes in the bones and teeth due to exposure to the environment, usually the subaerial environment, prior to burial including bleaching, breakage, flaking, etc.

Diagenesis - post-burial changes involved in “fossilization” including permineralization, replacement, compaction, etc.


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(from Martill, 1991, Bones as stones: contribution of vertebrate remains to the lithologic record. Pp. 270-292 in S. K. Donovan (ed). The Processes of Fossilization, Columbia University Press)

Where are fossils found?Fossils are sediments and are found in sedimentary depositional settings

1. River and stream channels (fluvial);

2. River floodplains (overbank deposits) (fluvial);

3. Lake beds (lacustrine);

4. Cave and fissure fillings (karst);

5. Marine environments below wave base (marine);

6. Beach sands and gravels (marginal marine).

Note that terrestrial vertebrate fossils are seldom found in the exact environment where the animal lived


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(from Martin, R. E. 1999. Taphonomy, a Process Approach. Cambridge University Press)

Fluvial deposition of vertebrate remains


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Taphonomic filtering between life and burial

Hyena transporting head and neck of a dead bovid.



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Taphonomic characteristics of assemblages


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Differential transportability of bones in fluvial systems


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Jonathan Bloch and Victor Mavrin prospecting Cretaceous outcrops at Tyulkoolee, Kazakhstan, 1995 (photo by P. David Polly)

Tyulkoolee Locality, Cretaceous, Kazakhstan

Paleosols (fossil soils) and flood plain deposits


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David Polly and Mark Goodwin excavating Thescelosaurus in Late Cretaceous Hell Creek Formation, July 1989.

Hell Creek, MontanaFlood-plain paleosols. Thescelosaurus skeleton being excavated from a layer in a former river overbank.


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QRA Field Trip to Norfolk. (photo by P. David Polly)

“Freshwater bed”, West Runton, United Kingdom

Lacustrine deposits. Organic-rich clays and silts with shell debris and gravels (dark layers at bottom of photograph) overlain by thick glacial till.


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(photo from The Natural History Museum, London)

Bacon Hole, EnglandKarst. Collapsed cave in coastal limestones. Cave sediments exposed after roof collapse.


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Typical cave depositional environmentAcid dissolution creates spaces in carbonate rocks, which then become filled with sediments. Continued dissolution and precipitation of calcium carbonate creates flowstone and travertine that covers layers of clays, sands, gravels and other debris


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(The Natural History Museum, London)

Fossils from cave depositsHyena maxilla encased in cave earth and travertine (flowstone)


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Reconstruction by Karen Carr (c Indiana State Museum)

Harrodsburg Fissure, IndianaKarst fissure filling with jaguar, saber-toothed cat, peccaries and other organisms found along Highway 37 south of Bloomington.


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Photo credit

Society of Vertebrate PaleontologyLargest international professional society of vertebrate paleontologists

SVP publishes the Journal of Vertebrate Paleontology

SVP Annual Meeting is where approximately 1,200 vertebrate paleontologists present their research(this year: Las Vegas, November 2-5)

Promotes research and protection of vertebrate fossils for scientific purposes

SVP website: www.vertpaleo.org

http://www.vertpaleo.org

http://www.vertpaleo.org


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SVP Statement on Professional Ethics in Vertebrate Paleontology

Members Ethics

Member Bylaw on Ethics StatementARTICLE 12. CODE OF ETHICSPreambleSeveral goals for the Society of Vertebrate Paleontology follow from its mission statement (Articles of Incorporation, Article 2, Section 1):

1. To advance the science of vertebrate paleontology throughout the world;2. To serve the common interests and facilitate the cooperation of all persons concerned with the history, evolution, ecology, comparative anatomy and taxonomy of

vertebrate animals, as well as the field occurrence, collection and study of fossil vertebrates and the stratigraphy of the beds in which they are found;3. To support and encourage the discovery, conservation and protection of vertebrate fossils and fossil sites;4. To foster the scientific, educational and personal appreciation and understanding of vertebrate fossils and fossil sites by avocational, student and professional

paleontologists and the general public.

Fossil vertebrates are usually unique or rare, nonrenewable scientific and educational resources that, along with their accompanying contextual data, constitute part of our natural heritage. They provide data by which the history of vertebrate life on earth may be reconstructed and are one of the primary means of studying evolutionary patterns and processes as well as environmental change.

Section 1. Professional standards in collection of fossilsIt is the responsibility of vertebrate paleontologists to strive to ensure that vertebrate fossils are collected in a professional manner, which includes the detailed recording of pertinent contextual data, such as geographic, stratigraphic, sedimentologic and taphonomic information.

Section 2. Adherence to regulations and property rightsIt is the responsibility of vertebrate paleontologists to assist government agencies in the development of management policies and regulations pertinent to the collection of vertebrate fossils, and shall comply with those policies and regulations during and after collection. The necessary permits on all lands administered by federal, state, and local governments, whether domestic or foreign, must be obtained from the appropriate agency(ies) before fossil vertebrates are collected. Collecting fossils on private lands must be done only with the landowner's consent.

Section 3. Fossil preparationFossil vertebrate specimens should be prepared by, or under the supervision of, trained personnel.

Section 4. Deposition of fossil specimensScientifically significant fossil vertebrate specimens, along with ancillary data, should be curated and accessioned in the collections of repositories charged in perpetuity with conserving fossil vertebrates for scientific study and education (e.g., accredited museums, universities, colleges and other educational institutions).

Section 5. Publication and educationInformation about vertebrate fossils and their accompanying data should be disseminated expeditiously to both the scientific community and the interested general public.

Section 6. Commercial sale or tradeThe barter, sale or purchase of scientifically significant vertebrate fossils is not condoned, unless it brings them into, or keeps them within, a public trust. Any other trade or commerce in scientifically significant vertebrate fossils is inconsistent with the foregoing, in that it deprives both the public and professionals of important specimens, which are part of our natural heritage.


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Laws protecting vertebrate fossils

Laws vary from state to state, and country to country

Indiana has no law or regulation protecting vertebrate fossils

Vertebrate fossils are protected on US land by Omnibus Lands Act of 2009, which includes the Paleontological Resources Preservation act (Public Law 111-11). This makes the following stipuations

1. A permit is required to collect vertebrate fossils on US public lands

2. Permits are issued to research groups

3. Fossils collected are to remain in the public trust and must be curated with associated stratigraphic and locality data into a museum research collection that is open to researchers and which is committed to preserving fossils in perpetuity

4. The act provides that common plant and invertebrate fossils may be collected for personal non-commercial use without permits


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Summary

Vertebrate fossils are seldom preserved in the environments in which the animals lived

The vertebrate fossil record probably has several systematic biases:

* lowland and marginal marine communities are well-represented* upland (e.g., alpine), mid-continent, and flying communities are under-represented* regions with thick modern vegetation (e.g., the tropics) tend to be under-studied* regional preservation is biased by past erosion and deposition, including the availability of sedimentary basins and burial by glacial till

Vertebrate fossils are rare, the stratigraphic and depositional context is important, and they are subject to commercial pillage so they are increasingly protected for scientific uses


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Scientific papers for further reading

Behrensmeyer, A. K. 1978. Taphonomic and ecologic information from bone weathering. Paleobiology, 4: 150-162.

Behrensmeyer, A. K. 1988. Vertebrate preservation in fluvial channels. Palaeogeography, Palaeoclimatology, Palaeoecology, 63: 183-199.

Franzen, J. L., P. D. Gingerich, J. Habersetzer, J. H. Hurum, W. von Koenigswald, and B.H. Smith. 2009. Complete primate skeleton from the Middle Eocene of Messel in Germany: Morphology and paleobiology. PLoS ONE, 4: e5723.

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