Unravelling Phanerozoic evolution of radial to rosette trace fossils

Abstract

Feeding trace fossils, produced by either deposit or detritus feeders and showing radial to rosetted morphology, are all included in the same architectural category. These radial to rosette ichnofossils are widely recorded worldwide throughout the Phanerozoic and have attracted the attention of numerous ichnologists for decades. Construction of a database summarizing occurrences of radial to rosette trace fossils through the Phanerozoic shows that representatives of this category occurred for the first time during the Fortunian, which accounts for the appearance of at least 12% of the total number of ichnogenera in this category. Overall, 32% of all known rosette ichnogenera resulted from the Cambrian Explosion. A second ichnodiversity increase took place (20%) during the Ordovician. Subsequent to the Great Ordovician Biodiversification Event, this architectural category shows minor fluctuations in ichnodiversity resulting in a long‐term plateau. The apparent decline in ichnodiversity by the end of the Cenozoic could reflect a taphonomic artefact resulting from the difficulties of identifying cumulative trace fossils in highly bioturbated modern sediments. Our data set indicates that several radial to rosette ichnogenera (e.g. Arenituba, Dactylophycus, Gyrophyllites, Phoebichnus, Volkichnium) occurred first in shallow‐marine settings and then migrated to either deeper‐water or marginal‐marine environments, while others (e.g. Asterichnus, Cladichnus, Dactyloidites) apparently first occurred in deep‐sea environments and then migrated to shallower waters.

Trace fossils, algae, invertebrate remains and new U-Pb detrital zircon geochronology from the lower Cambrian Torneträsk Formation, northern Sweden

“…Treptichnus isp. specimen but tend to have a distinctive vertical or oblique source burrow (Muñoz et al 2019) or a more prominently raised central burrow or plug (Joseph et al 2012). We retain this specimen as a separate informal ichnotaxon here, since the trace is incomplete but the segments are relatively large compared to typical T. pedum examples from the Torneträsk Formation, and it remains unclear whether the lobes were part of a tight spiral horizontal trace or a series of radial excavations surrounding a central vertical burrow.…”

“…If the described forms consist of burrows radiating from a central shaft, there are also similarities to Radiichnus Karaszewski, 1973, but the latter is known only from Jurassic offshore deposits of Poland. Muñoz et al (2019) recently summarized the diversity and spatio-temporal distribution of radial to rosette-shaped trace fossils noting that this group of ichnofossils occurs as low as the first stage of the Cambrian where they are best represented in shallow to deep shoreface settings.…”

Icnología de la Formación Lajas (Jurásico Medio), Grupo Cuyo, Cuenca Neuquina

“…A, C, D). Icnogénero Haentzschelinia, Vyalov (1964) Diagnosis: Sistema de galerías que no se superponen entre sí, que radian verticalmente de un eje vertical, rellenas activamente (spreite) (Muñoz et al, 2019), (Figura 5.3. C).…”

“…Sin embargo, en trabajos más recientes, se sugiere utilizar Dactyloidites para formas paleozoicas más simples, mientras se adscribe a los representantes más complejos mesozoicos y cenozoicos a Haentzchelinia Beláustegui et al, 2015;Buatois et al, 2017). Los potenciales productores de estas trazas pueden ser anélidos poliquetos, cangrejos, bivalvos o anfípodos (Muñoz et al, 2019). Descripción: Los ejemplares observados muestran un número variable de vueltas (mínimo 3, pero llegando hasta 9-10), y a veces tienen variaciones en el diámetro de la mismas.…”

“…B) Haenzchellinia en afloramiento, disposición en "roseta", vista estratal (Fm Lajas, Bajada Los Molles). C) Esquema de Haentzschelinia (tomado deMuñoz et al, 2019). D) Haentzschelinia en sección transversal en afloramiento (Fm.…”