Trace fossil of the second III: Asteriacites lumbricalis

The Tfots today is Asteriacites lumbricalis von Schlotheim, 1820, a resting trace produced by the (in)activity of ophiuroid echinoderms or brittle stars (Twitchett & Wignall 1996). I took these photographs from material found on the slopes of Costabella mountain in the Dolomites. These slabs are float from an outcrop exposing the Campil Member of the middle Werfen Formation (Lower Triassic, Early Olenekian). These trace are quite widespread in this member and known for more than a hundred years although they were erroneously recognised as body fossils in the first place (e.g. Wittenburg 1908). They come from more or less storm-dominated shoreface deposits composed of micaceous fine-grained sandstones and siltstones.

Thanks to a comment by David, I hoped to see some decent specimens during the recent field session and finally I was really lucky finding these well-preserved traces at the last day of the campaign. I never saw better ones at least in the literature so far.

Fig. 1: Asteriacites lumbricalis preserved as convex hyporelief (positive structure on a lower bedding plane). Black bar represents 5 mm.

Fig. 2: Asteriacites lumbricalis preserved as concave epirelief (negative structure on an upper bedding plane). Black bar represents 5 mm. Note the ripple-marks.

References:

Schlothheim, E.F. von, 1820: Petrefactenkunde auf ihrem jetzigen Standpunktedes Thier- und Pflanzenreichs der Vorwelt. Gotha, Becker, 437 p. durch die Beschreibung seiner Sammlung versteinerter und fossiler überreste.

Twitchett, R.J., Wignall, P.B., 1996: Trace fossils and the aftermath of the Permo-Triassic mass extinction: evidence from northern Italy. Palaeogeography, Palaeoclimatology, Palaeoecology 124, 137–152.

Wittenburg, P. von, 1908: Beiträge zur Kenntnis der Werfener Schichten Südtirols. Geologische und Palaeontologische Abhandlungen 8, 251–289.

Trace fossil of the second II: Brutalichnus brutalis Mikuláš et. al 2006

Today I picked this one because of its adorable name. Brutalichnus has been erected by Mikuláš et. al 2006 with a bunch of other neat traces like Nihilichnus and Machichnus from bone material found in Miocene Sediments near Chomutov (Czech Republic). All of these structures represent biting and gnawing traces on bones. Brutalichnus brutalis is interpreted by the authors as breakage due to bites of animals in order to feed on cancellous bones which are rich in organic material. Evidence for this hypothesis is provided by small radial patterns at the points where the bone is broken. It proves that the bones did not simply collapse as a result of compaction.

Fig. 1: Brutalichnus brutalis on a mandible (Mikuláš et al. 2007).

Fig. 2: The suggested trace maker action being responsible for the observed morphology (Mikuláš et al. 2007)

Reference
Mikuláš R., Kadlecová E., Fejfar O., Dvořák Z. (2007): Three New Ichnogenera of Biting and Gnawing Traces on Reptilian and Mammalian Bones: A Case Study from the Miocene of the Czech Republic. Ichnos, 13, p. 113–127. link

To close this post you may enjoy the audio version of Brutalichnus brutalis: Converge's Fault and Fracture.

Dudes...

...I should be busy right now: I have to finish my final mapping project in order to complete my studies by the end of december. Furthermore, I will have an interview for a PhD-student position but I won't tell anything until I know how everything worked out. All what I can say right now is that it is a darn interesting project...we will see!

Just to post something (semi)relevant let me introduce you to a new categorie on Nolögic:

Trace fossil of the second

Cruziana problematica Schindewolf, 1928

Coin for scale = 27 mm

I post this one because it is included in the banner of the blog-title. We found these ribbon-shaped bilobate trails on a large float block in Wadi Al Hisa/ Jordan. These traces record superficial grazing or very shallow deposit feeding bahviour performed by small arthropods (?small Trilobites). The surface is a lower bedding plane. You look at a positive hyporelief. The whole surface is covered by hundreds of specimens and even more specimens of their little brothers Rusophycus carbonarius (the little coffee beans). They are Middle Cambrian (Stage 5 or Drumian) in age and are found in a rather marginal marine environment. However, this ichnospecies is reported from marine as well as terrestrial subaquatic deposits and ranges in age from early Cambrian to Cretaceous.