Name/Title
Pinnate Leaf FossilEntry/Object ID
07.57.23Description
This is a pinnate compound leaf on stem which is a type of fern in sandstone.
Pinnate is a term used to describe feather-like or multi-divided features arising from both sides of a common axis in plant or animal structures, and comes from the Latin word pinna for "feather". A similar term is pectinate, which refers to a comb-like arrangement of parts (arising from one side of an axis). The term contrasts somewhat with palmate, in which the parts or structures radiate out from a common point.
Leaf fossils in this case are carbon films that remain on the bedding surfaces of fine-grained sediments. Fossilization happened after the leaves sank to the bottom of a pond or lake and were later buried by additional fine-grained sediments. With burial, the leaves were compressed and the sediment surrounding them solidified. Eventually these fine-grained sediments became shale or mudstone. When all the volatile organic material in the living leaf was pressed out, only a thin carbon residue was left in the sediment, marking the outline and veins of the leaf.
Rock and Mineral Data (Silica):
Assemblage Zone: Sandstone
Chemical Composition: Si O2
Crystal System: Subhedral
Type of Fossils Present: Plants
Fracture: conchoidal
Grain Size: Medium
Hardness: 7 Quartz
Lithofacies: Tropical to subtropical
Luster: Vitreous
Pressure: Moderate
Rock Color: Dark
Rock Origin: Freshwater
Rock Type: Sedimentary
Specific Gravity: 2.6
Surface Process: Not apparent
Temperature: Low
Texture: fine grainCollection
Fossil CollectionAcquisition
Accession
07.57Source or Donor
Fossil CollectionAcquisition Method
DonationOther Names and Numbers
Other Number
Other Number: 2007.57.23Dimensions
Width
5 inDepth
1 inLength
11 inDimension Notes
Dimensions taken at widest points.
Dimensions above seem to be for the entire rock. The original entry list the "leaf [as] 4.5" long and 6" wide."
I don't know how the leaf can be said to be wider than the rock without some improper estimation going on, but several of the specimens from Tyler Corno have dimensions for the fossil listed as wider than the matrix rock they're found on. Most likely, the original cataloger was taking eyeball measurements, and Ms. Boyd's are more accurate.Location
Location
Display Case
PW-7Room
Petrified Wood RoomBuilding
Crater Rock MuseumCategory
ExhibitMoved By
Jillian Mather KettleyDate
January 22, 2025Notes
Inventory/ location
