Romundina

Romundina
Temporal range: Early Devonian
~419–400 Ma
Artist's reconstruction
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: †Placodermi
Order: †Acanthothoraci
Family: †Palaeacanthaspidae
Genus: †Romundina
Ørvig, 1975
Species:
†R. stellina
Binomial name
†Romundina stellina
Ørvig, 1975

Romundina is a small, heavily armored extinct genus of acanthothoracid placoderms which lived in shallow marine environments in the early Devonian (Lochkovian).[1][2] The name Romundina honors Canadian geologist and paleontologist Dr. Rómundur (Raymond) Thorsteinsson of Calgary, Alberta, Canada. Romundina are believed to have lived on Earth between 400 and 419 million years ago. The closest known relative to Romundina is the acanthothoracid Radotina.[2] The type and only described species is R. stellina.

The first specimen of Romundina was originally discovered by Swedish paleontologist Tor Ørvig in 1975 on Prince of Wales Island (Nunavut) in a formation that geologically dates back to the Gedinnian.[2] Only one known species of Romundina has been discovered which was named Romundina stellina by Ørvig. The species name stellina refers to stellate (derived from Latin word stella meaning star) tubercles that the Placoderm has ornamenting its dermal skeleton.[2] Romundina stellina is one of the earliest known acanthothoraciforms discovered to date.[2]

Recently, Romundina stellina has been heavily researched as it shows signs of having extremely primitive teeth, which structurally share characteristics of both dermal tubercles and the teeth of modern and fossil gnathostomes.[3] Although Romundina are known to be relatively small especially when compared to some large predatory placoderms of the time, it is still thought to be carnivorous due to the tooth-like structures on its gnathal and supragnathal plates.[4]

Romundina shares many characteristics of both cyclostomes and Gnathostomes to varying degrees. This reinforces the hypothesis that placoderms are a grade as they have some features more closely related to cyclostomes then other placoderms while other features are much more closely related to crown group Gnathostomes.[1][3]

  1. ^ a b Dupret, Vincent; Sanchez, Sophie; Goujet, Daniel; Ahlberg, Per Erik (2017-02-07). "The internal cranial anatomy of Romundina stellina Ørvig, 1975 (Vertebrata, Placodermi, Acanthothoraci) and the origin of jawed vertebrates—Anatomical atlas of a primitive gnathostome". PLOS ONE. 12 (2): e0171241. Bibcode:2017PLoSO..1271241D. doi:10.1371/journal.pone.0171241. ISSN 1932-6203. PMC 5295682. PMID 28170434.
  2. ^ a b c d e Ørvig, T. (1975). "Description, with special reference to the dermal skeleton, of a new radotinid arthrodire from the Gedinnian of Arctic Canada". Colloque International CNRS. 218: 41–71.
  3. ^ a b Cite error: The named reference :0 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference :6 was invoked but never defined (see the help page).