Treptichnus

Treptichnus Temporal range: 550–24  Ma PreꞒ Ꞓ O S D C P T J K Pg N
Burrows viewed from the side
Burrows viewed obliquely
Trace fossil classification
Ichnogenus:	Treptichnus Miller, 1889
Type ichnospecies
Treptichnus bifurcus Miller, 1889
Ichnospecies [1]
†T. apsorumRindsberg & Kopasa-Merkel, 2005 [2] †T. aequalternusSchlirf, 2000 †T. apsorumRindsberg et Kopaska-Merkel, 2005 †T. arcusWang et Wang, 2006 [3] T. bifurcusMiller, 1889 †T. coronatum(Crimes et Anderson, 1985) †T. lublinensisPaczesna, 1986 †T. meandrinusUchman, Bromley et Leszczyński, 1993 †T. pedum(Seilacher, 1955) †T. pollardiBuatois et Mángano, 1993 †T. rectangularisOrłowski et Żylińska, 1996 †T. streptosusChen et Liu, 2025 [4] †T. taijiangensisWang et Wang, 2006 [3] †T. triplexPalij, 1976 †T. vagans(Książkiewicz, 1977)
Synonyms
PlangtichnusMiller, 1889 ManykodesDzik, 2005 [5] AffinovendiaSokolov, 1984

Treptichnus is a genus of trace fossils (with modern analogues) representing a three-dimensional burrow. These fossil traces are known from marine, brackish, and freshwater deposits from the Ediacaran (550 million years ago) to the Upper Oligocene (24 mya). ^{[6] [4] [7]}

Treptichnus represents the oldest known example of a complex, three-dimensional burrow. Its ichnospecies, Treptichnus pedum, is of major paleontological importance as it defines the global boundary between the Ediacaran and Cambrian periods (539 mya). ^{[8] [9] [10]}

Etymology

The name Treptichnus is derived from the Greek words trépō (τρέπω), meaning "to turn", and íchnos (ἴχνος), meaning "trace", forming the literal translation "turned trace", which describes the fossil's distinctive zigzag burrow pattern.

Description

Treptichnus pedum fossil marking the Cambrian-Ediacaran GSSP

The as a shallow mole-tunnel-like burrow produced just below the sediment surface and consists of a series of horizontal tubular segments where one end connects to the previous segment, and the other is oriented upwards, providing an opening to the surface. The segments can be straight or curved, and arranged in a linear or zigzagging pattern. ^{[2] [6] [5]}

It is hypothesised that the trace-makers systematically probed the sediment in search of nutrients, while the openings at the ends of the burrow segments could have served to collect food from the surrounding sediment surface or to ventilate the burrow. ^{[5] [11]}

No body fossils of the Treptichnus trace-makers have been found preserved within the burrows. It is believed that various organisms such as worms, crustaceans, and insect larvae could have produced these traces. Some late Ediacaran and Cambrian Treptichnus burrows are similar to traces made by modern priapulids, suggesting that this animal group may have originated as early as the Ediacaran Period. ^{[12] [11]}

Fossil traces from continental freshwater deposits, known from the Carboniferous to the Oligocene, most likely belonged to insect larvae, analogous to modern burrows produced by chironomids larvae. ^{[2] [13]}

References

1. "Treptichnus Miller, 1889". fossiilid.info.
2. Rindsberg, A. K.; K.-M., Martin (2005). "Treptichnus and Arenicolites from the Steven C. Minkin Paleozoic footprint Site (Langsettian, Alabama, USA)". Pennsylvanian Footprints in the Black Warrior Basin of Alabama: Alabama Paleontological Society Monograph no. 1. United States of America: University of Alabama Printing Services: 121–141.
3. Wang, Yue; Wang, Pingli (2006). "Ichnofossil Treptichnus from the Kaili Formation at Taijiang County, Guizhou Province". Geological Review. 52 (1).
4. Chen, Z.; Liu, Y. (2025). "Advent of three-dimensional sediment exploration reveals Ediacaran-Cambrian ecosystem transition". Science Advances. 11 (44) eadx9449. doi:10.1126/sciadv.adx9449. PMC   12571085 . PMID   41160697.
5. Dzik, Jerzy (2005). "Behavioral and Anatomical Unity of the Earliest Burrowing Animals and the Cause of the 'Cambrian Explosion'" (PDF). Paleobiology. 31 (3): 503–521. doi:10.1666/0094-8373(2005)031[0503:BAAUOT]2.0.CO;2.
6. Getty, P.R.; McCarthy, T.D.; Hsieh, S.; Bush, A.M. (2016). "A new reconstruction of continental Treptichnus based on exceptionally preserved material from the Jurassic of Massachusetts". Journal of Paleontology. 90 (2): 269–278. doi:10.1017/jpa.2016.20.
7. Uchman, Alfred; Pika-Biolzi, Milena; Hochuli, Peter A. (2004). "Oligocene trace fossils from temporary fluvial plain ponds: An example from the Freshwater Molasse of Switzerland" (PDF). Eclogae Geologicae Helvetiae. 97: 133–148. doi:10.1007/s00015-004-1111-z.
8. Subcommission on Neoproterozoic Stratigraphy - URL retrieved June 22, 2009
9. International Commission on Stratigraphy, International Chronostratigraphic Chart, 2012, http://www.stratigraphy.org/column.php?id=Chart/Time%20Scale
10. Singh, Birendra Pratap; Bhargava, Om N.; Sharma, Choudhurimayum; Ravi; Chaubey, Ravi; Prasad, Subhay; Negi, Ranveer; Kishore, Naval (2017-01-10). "Treptichnus Ichnogenus from the Cambrian of India and Bhutan: Its Relevance to the Precambrian-Cambrian Boundary". Journal of the Palaeontological Society of India. 62. doi:10.1177/0971102320170104.
11. Turk, K.A.; Wehrmann, A.; Laflamme, M.; Darroch, S.A.F. (2024). "Priapulid neoichnology, ecosystem engineering, and the Ediacaran–Cambrian transition". Palaeontology. 67 (1): 39–50. doi: 10.1111/pala.12721 .
12. Vannier, J.; Calandra, I.; Gaillard, C.; Zylinska, A. (2010). "Priapulid worms: Pioneer horizontal burrowers at the Precambrian-Cambrian boundary". Geology. 38 (8): 711–714. Bibcode:2010Geo....38..711V. doi:10.1130/G30829.1.
13. Uchman, A. (2005). "Treptichnus-like traces made by insect larvae (diptera: chironomidae, tipulidae)". Pennsylvanian Footprints in the Black Warrior Basin of Alabama. 1: 143–146.