Paired fossil burrows from Los Cabos Group of Spain, Cambrian-Ordovician: a new ichnotaxon or Rosselia prolifera?

Location

Bent Corridor, Science Center

Document Type

Poster - Open Access

Start Date

5-1-2026 12:00 PM

End Date

5-1-2026 2:00 PM

Abstract

The Middle Cambrian to Lower Ordovician Los Cabos Group from Spain constitutes a >6000 m-thick succession deposited in the margin of Northern Gondwana. The succession is represented by sandstone and mudstone associated with deltaic systems affected by tides, waves, and storms. An unusual occurrence of a fossil burrow known as Rosselia was studied, in order to understand its morphology, potential producers, and ethology. Rosselia is usually represented by a single vertical tube that has a concentric infill, whereas the studied specimens are found in a paired form. The specimens occur in ripple cross-laminated and cross-bedded flaser sandstone interpreted to be deposited in tide-dominated environments. They consist of vertical to inclined U- or Y-shaped burrows with a funnel shaped aperture that tapers down to the central cylindrical tube. The causative tube either extends down and forms a U-shape, connecting two vertical branches in an arcuate morphology, or the central tube splits off and creates a Y-shape. The causative burrows have a diameter ranging between 2-4 cm, and 2-6 cm deep. The likely tracemaker for Rosselia are detritus-eating terebellid polychaetes. The studied Rosselia is similar to Cylindrichnus with the concentric central tube, but Rosselia have the distinct funnel shaped bulbs. Cylindrichnus has a more arcuate U-shape and is wider than it is deep, while Rosselia are deeper than they are long with a vertical orientation. For these reasons, we are proposing that these trace fossils described here are a new U- and Y-shaped species of Rosselia, or belong to Rosselia prolifera.

Keywords:

Trace fossils, Paleontology, Sedimentology

Notes

Presenter: Paige Grossenbacher

Major

Geoscience

Project Mentor(s)

Maximiliano Paz, Geosciences

2026

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May 1st, 12:00 PM May 1st, 2:00 PM

Paired fossil burrows from Los Cabos Group of Spain, Cambrian-Ordovician: a new ichnotaxon or Rosselia prolifera?

Bent Corridor, Science Center

The Middle Cambrian to Lower Ordovician Los Cabos Group from Spain constitutes a >6000 m-thick succession deposited in the margin of Northern Gondwana. The succession is represented by sandstone and mudstone associated with deltaic systems affected by tides, waves, and storms. An unusual occurrence of a fossil burrow known as Rosselia was studied, in order to understand its morphology, potential producers, and ethology. Rosselia is usually represented by a single vertical tube that has a concentric infill, whereas the studied specimens are found in a paired form. The specimens occur in ripple cross-laminated and cross-bedded flaser sandstone interpreted to be deposited in tide-dominated environments. They consist of vertical to inclined U- or Y-shaped burrows with a funnel shaped aperture that tapers down to the central cylindrical tube. The causative tube either extends down and forms a U-shape, connecting two vertical branches in an arcuate morphology, or the central tube splits off and creates a Y-shape. The causative burrows have a diameter ranging between 2-4 cm, and 2-6 cm deep. The likely tracemaker for Rosselia are detritus-eating terebellid polychaetes. The studied Rosselia is similar to Cylindrichnus with the concentric central tube, but Rosselia have the distinct funnel shaped bulbs. Cylindrichnus has a more arcuate U-shape and is wider than it is deep, while Rosselia are deeper than they are long with a vertical orientation. For these reasons, we are proposing that these trace fossils described here are a new U- and Y-shaped species of Rosselia, or belong to Rosselia prolifera.