Early Miocene coral reef-associated bryozoans from Colombia. Part I: Cyclostomata, “Anasca” and Cribrilinoidea Cheilostomata

Abstract

This is the first of two comprehensive taxonomic works on the early Miocene (ca. 23–20 Ma) bryozoan fauna associated with coral reefs from the Siamaná Formation, in the remote region of Cocinetas Basin in the La Guajira Peninsula, northern Colombia, southern Caribbean. Fifteen bryozoan species in 11 families are described, comprising two cyclostomes and 13 cheilostomes. Two cheilostome genera and seven species are new: Antropora guajirensis n. sp., Calpensia caribensis n. sp., Atoichos magnus n. gen. n. sp., Gymnophorella hadra n. gen. n. sp., Cribrilaria multicostata n. sp., Cribrilaria nixor n. sp., and Figularia bragai n. sp. Eight species are identified only at genus level and remain in open nomenclature. Of the species found, 27% have erect colonies and 73% encrusting colonies. Both types contributed to the reef framework and produced sediment. The observed bryozoan diversity was higher in the barrier reefs than in the lagoonal patch reefs. UUID: http://zoobank.org/5c8468ef-31b0-4e7e-ba93-60a2e2f30b76.

Early Miocene coral reef-associated bryozoans from Colombia. Part II: “Ascophora” Cheilostomatida

“…Some works point to a late Oligocene age (Rollins, *Corresponding author 1965;Cardenas et al, 2020;Jaramillo et al, 2020), while others suggest a diachronic deposition that reached the early Miocene (Duque-Caro, 1974;Teatin, 1991;Silva-Tamayo et al, 2017). Here, we follow Flórez (2020) and Flórez et al (2021) who suggested an early Miocene age based on larger benthic foraminifera, and the dating provided by Silva-Tamayo et al (2017) based on strontium isotopes of coralline algae from the same localities studied here. A revision of the lateral facies change, within the early Miocene, is needed in some parts of the Cocinetas Basin to understand the stratigraphic relationships between the Siamaná and Uitpa formations and clarify the age of the last onlapping phases of the former; however, this is beyond the scope of the present work.…”

“…These coral communities thrived in tropical waters, at depths of 2-30 m, with low turbidity, low energy, and limited siliciclastic input (Flórez et al, 2019a, b;Flórez, 2020). Associated with them, we found 32 bryozoan species (Flórez et al, 2021;this paper). New species account for 31% (10 species) of the whole assemblage.…”

“…The catalog numbers and metadata of the specimens studied are supplied in Appendix 2. More details about the methods are provided in Flórez et al (2021).…”

“…Localities, stations and coordinates of the Siamaná Formation in the studied area. Geologic ages inferred from strontium isotopes in coralline algae (Silva-Tamayo et al, 2017), and faunistic assemblages found in the studied outcrops (Flórez et al, 2021)…”

“…and coralline algae, co-occurring with Smittipora sp. indet (Flórez et al, 2021). and Trypostega sp.…”