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November 12, 2011: THE FOSSIL RECORD: Fossils and How
They Form
Instructor:Jonathan HendricksAssistant Professor of Paleontology, SJSU,
Dept. GeologyEmail: [email protected]
November 12, 2011: THE FOSSIL RECORD: Fossils and How
They Form
Instructor:Jonathan HendricksAssistant Professor of Paleontology, SJSU,
Dept. GeologyEmail: [email protected]
What Are Fossils?What Are Fossils?Fossil: the remains or evidence of life
from a previous geological time.
“Fossil” is from the Latin word fossilis, meaning “dug up”.
Remains of past life do not have to have been turned to stone to be fossils!
Fossil: the remains or evidence of life from a previous geological time.
“Fossil” is from the Latin word fossilis, meaning “dug up”.
Remains of past life do not have to have been turned to stone to be fossils!
Slide shows two figures. One of a drawing by Gesner of a fossil and modern crab; one of a photograph of Gesner’s fossil crab.
Slide shows two figures. One of a drawing by Gesner of a fossil and modern crab; one of a photograph of Gesner’s fossil crab.
Comparison of Fossil and Modern Crab
Comparison of Fossil and Modern Crab
Gesner was the first person to illustrate fossils (1565).Gesner was the first person to illustrate fossils (1565).
Slide shows a fossil shark tooth.Slide shows a fossil shark tooth.
“Tongue Stones”“Tongue Stones”
Tongues of snakes or dragons??
Tongues of snakes or dragons??
Figure from: Pimiento C, Ehret DJ, MacFadden BJ, Hubbell G (2010). PLoS ONE 5(5): e10552. doi:10.1371/journal.pone.0010552.g002
Key QuestionsKey Questions Are fossils a result of Vis plastica?
Do fossils have an organic origin?
When did they get into rocks? Before or after the rock formed?
What caused them to be petrified?
Slide shows a picture of a shark’s tooth and a drawing (by Steno) of a shark’s head, full of teeth.
Slide shows a picture of a shark’s tooth and a drawing (by Steno) of a shark’s head, full of teeth.
Steno’s RevelationSteno’s Revelation Nicolaus Steno (1631-1687),
Danish anatomist. Dissected a shark. Tongue stones look like sharks
teeth because they were sharks teeth!
How did sharks’ teeth get into rock?
Steno’s Revelation: surrounding rock must have been soft when teeth were deposited and later became hardened.
Overturned idea that rocks have been exactly the same as we see them today since the earliest days of the creation….
Nicolaus Steno (1631-1687), Danish anatomist.
Dissected a shark. Tongue stones look like sharks
teeth because they were sharks teeth!
How did sharks’ teeth get into rock?
Steno’s Revelation: surrounding rock must have been soft when teeth were deposited and later became hardened.
Overturned idea that rocks have been exactly the same as we see them today since the earliest days of the creation….
Darwin Said….Darwin Said….
“For my part, following out Lyell’s metaphor, I look at the geological record as a history of the world imperfectly kept, and written in a changing dialect; of this history, we possess the last volume alone, relating only to two or three countries. Of this volume, only here and there a short chapter has been preserved; and of each page, only here and there a few lines.” -- Darwin (1859)
“For my part, following out Lyell’s metaphor, I look at the geological record as a history of the world imperfectly kept, and written in a changing dialect; of this history, we possess the last volume alone, relating only to two or three countries. Of this volume, only here and there a short chapter has been preserved; and of each page, only here and there a few lines.” -- Darwin (1859)
How Good is the Fossil Record?How Good is the Fossil Record? Answer is complex and depends on the
question being asked. Most ancient species never left a fossil
record. Many species that did leave a fossil
record will never be collected or observed.
The rock & fossil records are incomplete.
Our questions must keep these factors in mind.
Answer is complex and depends on the question being asked.
Most ancient species never left a fossil record.
Many species that did leave a fossil record will never be collected or observed.
The rock & fossil records are incomplete.
Our questions must keep these factors in mind.
Two Major Types of FossilsTwo Major Types of FossilsTwo major types of fossils:
1. Body fossils: Evidence of the morphologies (body forms) of ancient organisms.
2. Trace fossils: Evidence of the activities of ancient organisms.
Two major types of fossils:
1. Body fossils: Evidence of the morphologies (body forms) of ancient organisms.
2. Trace fossils: Evidence of the activities of ancient organisms.
Slide shows two photographs. One is of a museum drawer full of ammonoid fossils. The other shows a photograph of a T. rex skeleton.
Slide shows two photographs. One is of a museum drawer full of ammonoid fossils. The other shows a photograph of a T. rex skeleton.
Preservation of Body FossilsPreservation of Body FossilsFossil record composed mostly of mineralized hard-parts (e.g., shells & bones).
Fossil record composed mostly of mineralized hard-parts (e.g., shells & bones).
Slide shows two photographs. One is of a soft-bodied arthropod from the Cambrian of Utah, showing internal organs. The other is a photograph of a fossil jellyfish from PLoS ONE.
Slide shows two photographs. One is of a soft-bodied arthropod from the Cambrian of Utah, showing internal organs. The other is a photograph of a fossil jellyfish from PLoS ONE.
Preservation of Body FossilsPreservation of Body FossilsFleshy “soft-parts” rarely preserved.
Typically preserved only in absence of O2.
Fleshy “soft-parts” rarely preserved.
Typically preserved only in absence of O2.
Fig. 3 from Cartwright P, Halgedahl SL, Hendricks JR, Jarrard RD, Marques AC, et al. (2007) Exceptionally Preserved Jellyfishes from the Middle Cambrian. PLoS ONE 2(10): e1121. doi:10.1371/journal.pone.0001121
Slide shows two photographs. One is of permineralized fossil plant remains under a microscope, showing cellular level detail. The other is a photograph of a petrified log from Florissant, CO.
Slide shows two photographs. One is of permineralized fossil plant remains under a microscope, showing cellular level detail. The other is a photograph of a petrified log from Florissant, CO.
PermineralizationPermineralizationPetrified wood and
many bones have this type of preservation.
Empty pore spaces are filled with inorganic material, often silica or calcite.
Petrified wood and many bones have this type of preservation.
Empty pore spaces are filled with inorganic material, often silica or calcite.
Petrified Wood (Tree Stump)
Slide includes two photographs. One shows of snail shells and external molds of snail shells. The other shows an endocast of a mammal brain.
Slide includes two photographs. One shows of snail shells and external molds of snail shells. The other shows an endocast of a mammal brain.
Molds and CastsMolds and Casts
Mold = cavity
Cast = filled cavity
Mold = cavity
Cast = filled cavity
Body fossils (shells) and external molds (impressions) of shells.
Endocast of fossil camel brain.
CarbonizationCarbonization
Residue of concentrated carbon that remains after other organic remains have been lost.
Residue of concentrated carbon that remains after other organic remains have been lost.
Slide shows photographs of a carbonized fossil plant leaf and insect.
Slide shows photographs of a carbonized fossil plant leaf and insect.
Unaltered RemainsUnaltered Remains
Slide shows three figures. One shows mammoth hair. Another shows a frozen mammoth bone. The last shows a figure of elephant relationships based upon DNA extracted from a frozen bone.
Slide shows three figures. One shows mammoth hair. Another shows a frozen mammoth bone. The last shows a figure of elephant relationships based upon DNA extracted from a frozen bone.
Mammoth hair.
Above and lower left igures from Rogaev EI, Moliaka YK, Malyarchuk BA, Kondrashov FA, Derenko MV, et al. (2006) Complete Mitochondrial Genome and Phylogeny of Pleistocene MammothMammuthus primigenius. PLoS Biol 4(3): e73. doi:10.1371/journal.pbio.0040073
33,000 year old frozen mammoth bone from Siberia
Unaltered Fossil Shells with Color Patterns Visible Under UV Light
Unaltered Fossil Shells with Color Patterns Visible Under UV Light
Conus oniscusCercado Fm.PRI (Loc. TU1230)
Slide shows three figures. One is of worm burrows. The other two show dinosaur footprints.
Slide shows three figures. One is of worm burrows. The other two show dinosaur footprints.
Movement Trace FossilsMovement Trace Fossils
Dinosaur track figures from Wilson JA, Marsicano CA, Smith RMH (2009) Dynamic Locomotor Capabilities Revealed by Early Dinosaur Trackmakers from Southern Africa. PLoS ONE 4(10): e7331. doi:10.1371/journal.pone.0007331
Dinosaur tracks.
Worm burrows.
Slide shows two photographs of dinosaur coprolites including a large specimen and a microscopic photo taken of a coprolite, showing dissolved bone inside.
Slide shows two photographs of dinosaur coprolites including a large specimen and a microscopic photo taken of a coprolite, showing dissolved bone inside.
Digestive Trace FossilsDigestive Trace Fossils
From USGS.
“Coprolite”
Slide shows two photographs. One shows a drill hole made by a snail on a clam shell. The other shows a scar made by a crab on a snail shell.
Slide shows two photographs. One shows a drill hole made by a snail on a clam shell. The other shows a scar made by a crab on a snail shell.
Predation Trace FossilsPredation Trace Fossils
Drill holeRepairscar
Slide contains two figures. One shows paintings of recently discovered dinosaurs. The other shows the bones actually discovered from those dinosaurs.
Slide contains two figures. One shows paintings of recently discovered dinosaurs. The other shows the bones actually discovered from those dinosaurs.
Most Dinosaurs are Known from Only a Few Bones
Most Dinosaurs are Known from Only a Few Bones
Figures from Hocknull et al. (2009)
Hocknull SA, White MA, Tischler TR, Cook AG, Calleja ND, et al. (2009) New Mid-Cretaceous (Latest Albian) Dinosaurs from Winton, Queensland, Australia. PLoS ONE 4(7): e6190. doi:10.1371/journal.pone.0006190
BrontomerusBrontomerus
New dinosaur from Utah.
New dinosaur from Utah. Slide shows two images of
Brontomerus: one showing a skeleton highlighting the few bones that were found and the second showing an artists reconstruction of the dinosaur kicking a predatory dinosaur.
Slide shows two images of Brontomerus: one showing a skeleton highlighting the few bones that were found and the second showing an artists reconstruction of the dinosaur kicking a predatory dinosaur.
“Fig. 1. Skeletal inventory of the camarasauromorph sauropodBrontomerus mcintoshi gen. et sp. nov. from the Lower Cretaceous Cedar Mountain Formation of Utah, in left lateral view. Preserved elements are white, missing elements are reconstructed in gray. After aCamarasaurus grandis reconstruction kindly provided by Scott Hartman.”
Taylor, M. P., M. J. Wedel, and R. L. Cifelli. 2009. A New Sauropod Dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, USA. Acta Palaeontologica Polonica 56(1):75-98. 2011 doi: 10.4202/app.2010.0073.
