Name/Title
CalamitesEntry/Object ID
07.58.59Description
Chemical Composition: Si O2
Crystal System: Anhedral
Description: Genus: Calamites
Common name: Equisitum
Age:Late Pennsylvanian 320 mya
Location data: Four Corners Formation, Kentucky, USA
Description: A khaki colored sandstone "pith cast" with vertical ribbing a "calamites" (from the genus extinct member of the sphenophyta family) the only living genus of which is equisitum, commonly called horsetail.
Size:3.750"x 3.750"x 4.750"
** Calamites that grew in the Late Pennsylvanian, about 300 mya . These tree like rushes had jointed stems and could grow 30 feet height. The pith cast of a calamites stem, which shows the inner structure of the woody cylinder surrounding te plant's pith. This cast gives a misleading impression of the size of a Calamites stem, when alive the plant's pith was surrounded by a wide layer of secondary woody growth and a cortex. The only living relative of calamites are a small rush called Equisitum which is commonly known as horse tail or bottle brush.
Type of Fossils Present: Plants
Fracture: conchoidal
Grain Size: Fine
Hardness: 7 Quartz
Luster: Silky
Occurrence: The trunks of Calamites had a distinctive segmented, bamboo-like appearance and vertical ribbing. The branches, leaves and cones were all borne in whorls. The leaves were needle-shaped, with up to 25 per whorl.
Their trunks produced secondary xylem, meaning they were made of wood. The vascular cambium of Calamites was unifacial, producing secondary xylem towards the stem center, but not secondary phloem.
The stems of modern horsetails are typically hollow or contain numerous elongated air-filled sacs. Calamites was similar in that its trunk and stems were hollow, like wooden tubes. When these trunks buckled and broke, they could fill with sediment. This is the reason pith casts of the inside of Calamites stems are so common as fossils.
Pressure: Low-Moderate
Rock Color: Medium
Rock Origin: Marine/Freshwater
Rock Type: Sedimentary
Specific Gravity: 2.6
Surface Process: Not apparent
Streak: white
Temperature: Low
Texture: Fine grain texture
Variety: Calamites is a genus of extinct arborescent (tree-like) horsetails to which the modern horsetails (genus Equisetum) are closely related. Unlike their herbaceous modern cousins, these plants were medium-sized trees, growing to heights of more than 30 meters (100 feet). They were components of the understories of coal swamps of the Carboniferous period
Calamites correctly refers only to casts of the stem of Carboniferous/Permian sphenophytes, and as such is a form genus of little taxonomic value. There are two forms of casts, which can give mistaken impressions of the organims. The most common is an internal cast of the hollow (or pith-filled) void in the centre of the trunk. This can cause some confusion: firstly, it must be remembered that a fossil was probably surrounded with 4-5 times its width in (unpreserved) vascular tissue, so the organisms were much wider than the internal casts preserved. Further, the fossil gets narrower as it attaches to a rhizoid, a place where one would expect there to be the highest concentration of vascular tissue (as this is where the peak transport occurs). However, because the fossil is a cast, the narrowing in fact represents a constriction of the cavity, into which vascular tubes encroach as they widen.
Calamites is a genus of extinct arborescent (tree-like) horsetails to which the modern horsetails (genus Equisetum) are closely related.[1] Unlike their herbaceous modern cousins, these plants were medium-sized trees, growing to heights of 30–50 meters (100–160 feet).[2] They were components of the understories of coal swamps of the Carboniferous Period (around 360 to 300 million years ago).Collection
Petrified Wood CollectionAcquisition
Accession
07.58Source or Donor
Petrified Wood CollectionAcquisition Method
DonationOther Names and Numbers
Other Number
Old Number: F583; Other Number: 2007.58.59Dimensions
Width
3-3/4 inDepth
4-3/4 inLength
3-3/4 inDimension Notes
Dimension taken at widest pointsLocation
Location
Container
RightDrawer
BottomShelf
RightCabinet
Case #102Wall
East WallBuilding
Mentzer Hall - Petrified Wood RoomCategory
Permanent
