Diplocraterion

{{Ichnobox

| image = Tuscarora Formation Diplocraterion.jpg

| image_caption = Diplocraterion burrow (at left) from the Silurian-age Tuscarora Formation at Bald Eagle Mountain, Centre County, Pennsylvania. Specimen is ~22cm high.

| taxon = Diplocraterion

| authority =

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Image:Diplocraterion parallelum - Richter1926.gif in a Diplocraterion parallelum burrow.]]

Diplocraterion is an ichnogenus describing vertical U-shaped burrows having a spreite (weblike construction) between the two limbs of the U. The spreite of an individual Diplocraterion trace can be either protrusive (between the paired tubes) or retrusive (below the paired tubes). Some ichnospecies have both types (e.g., Diplocraterion yoyo).{{Cite journal|title = The trace fossils of the Baggy Beds (Upper Devonian) of North Devon, England|last = Goldring|first = Roland|date = 1962|journal = Paläontologische Zeitschrift|volume = 36|issue = 3–4|pages=232–251|doi = 10.1007/BF02986976| bibcode=1962PalZ...36..232G |s2cid = 140161473}} The presence/absence of funnel-shaped openings should not be used as an ichnotaxobase due to the high probability that the upper portions of the trace may have been eroded away. Observation of the orientation of Diplocraterion in the field is frequently used to determine the way up of rock strata at outcrop.{{cite web |title=Determining stratigraphic tops |url=https://www.geological-digressions.com/determining-stratigraphic-tops/ |website=Geological digressions |date=6 February 2019 |access-date=19 January 2020}}

There are several ichnospecies of Diplocraterion.

class="wikitable"

! colspan="2" |Some Ichnospecies of Diplocraterion

Ichnospecies

|Diagnosis

D. parallelumTorell, O., 1870. Petrificata Suecana Formationis Cambricae. Lunds. Univ. Arsskr. 6. Avdel. 2, No. VIII, p. 1-14.

|Parallel burrow walls and unidirectional spreite

D. helmerseniOpik, A., 1929. Studien uber das estnische Unterkambrium (Estonium). I-IV. Acta Comment. Univers. Tartuensis, A. 15(2), 56 p.

|U-tubes expand laterally at the base

D. biclavatum{{Cite journal|title = Some new species of fossils from the Cincinnati group and remarks upon some described forms|last = Miller|first = S.A.|date = 1875|journal = Cincinnati Quarterly Journal of Science|issue = 2|pages=349–355}}

|Arms of the U-tube extend below the curved base and form blind pouches

D. habichiLisson, C.I., 1904. Los Tigillites del Salto del Fraile y algunes Sonneratia del Morro Solar. Cuerpo Ingen. Minas del Peru, Bol No 17, 64 p.

|Arms of the U-tube diverge upward

D. polyupsilon{{Cite journal|title = Peculiar U-shaped tubes in sandstone near Crawfurdland Castle and in Gowkha Quarry, near Killwinning|last = Smith|first = J.|date = 1893|journal = Transactions of the Geological Society of Glasgow|issue = 9|pages=289–292}}

|Bidirectional spreite that constrict upward

D. yoyo

|U-tubes with both retrusive and protrusive spreiten

Ethology

The various ichnospecies of Diplocraterion provide a good example of how ethology (animal-substrate interactions and behavior) can be interpreted from trace fossils. Diplocraterion is a classic example of equilibrichnia (equilibrium traces).{{Cite book|title = Ichnology: Organism-Substrate Interactions in Space and Time|last1 = Buatois|first1 = Luis|publisher = Cambridge University Press|year = 2011|isbn = 978-0-521-85555-6|location = New York|page=358|last2 = Mangano|first2 = M. Gabriela}} These types of traces represent gradual adjustments to background sedimentation and erosion rates and reflect the efforts of the organisms to maintain a specific depth within the substrate. This movement within the substrate produces the two types of spreite (protrusive and retrusive) characteristic of Diplocraterion and other ichnotaxa (e.g., Rhizocorallium).

Most Diplocraterion show only protrusive spreit (e.g., D. parallelum, D. polyupsilon, D. biclavatum). These indicate that the trace was produced under predominantly erosive conditions where the organism was constantly burrowing deeper into the substrate as sediment was eroded from the top. D. yoyo has both protrusive and retrusive spreiten indicating highly variable conditions (erosional and depositional) leading to the need for the organisms to constantly adjust itself up and down within the substrate to maintain equilibrium and not become exposed or buried.

References

{{reflist | refs=

{{cite journal |doi= 10.2307/3514630 |author= Cornish, F.G. |journal= PALAIOS |volume= 1 |issue= 5 |pages= 478–491 |year= 1986 |title= The Trace-Fossil Diplocraterion: Evidence of Animal-Sediment Interactions in Cambrian Tidal Deposits |jstor=3514630|bibcode= 1986Palai...1..478C }}

{{cite journal |author= Fursich, F.T. |journal= Journal of Paleontology |volume= 48 |issue= 5 |title=On Diplocraterion Torell 1870 and the significance of morphological features in vertical, spreiten-bearing, U-shaped trace fossils |pages= 952–962 |year= 1974 |jstor=1303293}}

{{cite journal |author=Richter, Rudolf |year=1926 |title=Flachseebeobachtungen zur Paläontologie und Geologie. XII-XIV |journal=Senckenbergiana |volume=8 |pages=200–224 }}

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Diplocraterion

Ethology

See also

References

Further reading