''Carolowilhelmina geognostica'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

arthrodire Arthrodira (Greek for "jointed neck") is an Order (biology), order of extinct armored, jawed fishes of the class Placodermi that flourished in the Devonian period before their sudden extinction, surviving for about 50 million years and penetratin ...

placoderm Placoderms (from Ancient Greek πλάξ 'plax'', ''plakos'''Plate (animal anatomy), plate' and δέρμα 'derma'''skin') are vertebrate animals of the class (biology), class Placodermi, an extinct group of prehistoric fish known from Pal ...

fish that lived in the Late Eifelian epoch (of

Middle Devonian In the geological timescale, the Middle Devonian epoch (from 393.3 ± 1.2 million years ago to 382.7 ± 1.6 million years ago) occurred during the Devonian period, after the end of the Emsian age. The Middle Devonian epoch is subdivided into two ...

) of

Aragon Aragon ( , ; Spanish and ; ) is an autonomous communities of Spain, autonomous community in Spain, coextensive with the medieval Kingdom of Aragon. In northeastern Spain, the Aragonese autonomous community comprises three provinces of Spain, ...

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

. In life, ''C. geognostica'' was a long-snouted

pelagic fish Pelagic fish live in the pelagic zone of ocean or lake waters—being neither close to the bottom nor near the shore—in contrast with demersal fish that live on or near the bottom, and reef fish that are associated with coral reefs. ...

, superficially similar to the Australian ''

Rolfosteus ''Rolfosteus'' is an extinct monospecific genus of arthrodire placoderm from the Early Frasnian stage of the Late Devonian period, found at the Gogo Formation of Western Australia. Description ''Rolfosteus'' had a skull reaching , with tough pla ...

'' and the European '' Oxyosteus''. It is currently known only from an incomplete

cranium The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

that is about long. The fossil material is housed in the Natural Sciences museum of the

University of Zaragoza The University of Zaragoza, sometimes referred to as Saragossa University () is a public university with teaching campuses and research centres spread over the three provinces of Aragon (Spain). Founded in 1542, it is one of the List of oldest u ...

, Spain (Museo de ciencias Naturales de la Universidad de Zaragoza).

Discovery

Initial fragments belonging to ''Carolowilhelmina'' were accidentally uncovered by paleontologist Peter Carls in April 1971, after breaking a limestone nodule in an attempt to obtain a

Conodont Conodonts, are an extinct group of marine jawless vertebrates belonging to the class Conodonta (from Ancient Greek κῶνος (''kōnos''), meaning " cone", and ὀδούς (''odoús''), meaning "tooth"). They are primarily known from their hard ...

sample. The following day, fellow paleontologist Otto H. Walliser identified the fragments as

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

remains, as they had been washed clean by a creek below the section. The origin of the fragments, however, could not be identified, as a portion of the slope had slid down and covered it. This did prompt a search for fish remains elsewhere, resulting in the discovery of '' Grossius aragonensis''. by 1986, the creek had eroded at the sediment, revealing part of the fossil's rostrum. The fossil was collected in 1993. The genus is named after Carl and Wilhelm of Braunschweig, founders of the

Technical University of Braunschweig TU Braunschweig (, unofficially ''University of Braunschweig – Institute of Technology'') is the oldest ' (comparable to an institute of technology in the American system) in Germany. It was founded in 1745 as Collegium Carolinum and is a membe ...

, and was named on the university's 250th anniversary.

Description

''Carolowilhelmina'' is only known from a single, incomplete

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

. However, what is present in the fossil is well preserved. Carolowilhelmina was large, as the skull alone could have reached over half a meter in length. The skull also possesses a long snout of an uncertain length, since most of it had eroded away before its discovery. The snout has several thornlike spines running down it laterally. The skull possesses no teeth, but instead has a unique spongy knob-like structure in the mouth. As with ''

'', ''Carolowilhelmina'' possessed a long tubular rostral plate, with small postnasal plates and low inferognathal plates. Taxonomically, ''Carolowilhelmina'' seems closer to camuropiscids than to brachyderoids and '' Maideria''. However, the number of unique features seen in the skull, such as the spines, lack of teeth, and unique sensory line placement makes the familial placement of this

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

unclear.

Paleoecology

Living just before the

Kačák Event The Kačák Event (), also known as the Kačák-''otomari'' Event, is a widely recognised bioevent or series of events that occurred close to the end of the Eifelian Age of the Middle Devonian Epoch. It involved a global eustatic rise in sea level ...

, ''Carolowilhelmina'' inhabited an environment with a rapidly deepening Celtiberian sea alongside

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

fauna Fauna (: faunae or faunas) is all of the animal life present in a particular region or time. The corresponding terms for plants and fungi are ''flora'' and '' funga'', respectively. Flora, fauna, funga and other forms of life are collectively ...

represented by dacryoconarids,

bivalves Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consis ...

, small

brachiopod Brachiopods (), phylum (biology), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear e ...

s, and

ammonoids Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...

. The abundance of invertebrates in the region can infer the presence of floating algae, which may have also contributed to the abundance of organic matter preserved in the anoxic sediment. Other fish like '' Grossius,'' and the

conodont Conodonts, are an extinct group of marine jawless vertebrates belonging to the class Conodonta (from Ancient Greek κῶνος (''kōnos''), meaning " cone", and ὀδούς (''odoús''), meaning "tooth"). They are primarily known from their hard ...

''Tortodus kocklianus'' were present in this environment. ''Carolowilhelmina'' thus inhabited a

open ocean The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the surfa ...

environment, and when it

died Death is the end of life; the irreversible cessation of all biological functions that sustain a living organism. Death eventually and inevitably occurs in all organisms. The remains of a former organism normally begin to decompose sho ...

had sunk into an

anoxic Anoxia means a total depletion in the level of oxygen, an extreme form of hypoxia or "low oxygen". The terms anoxia and hypoxia are used in various contexts: * Anoxic waters, sea water, fresh water or groundwater that are depleted of dissolved ox ...

deep sea The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combination of low tempe ...

environment where it was untouched by boring or encrusting organisms. It is inferred to have preyed on the abundance of

life Life, also known as biota, refers to matter that has biological processes, such as Cell signaling, signaling and self-sustaining processes. It is defined descriptively by the capacity for homeostasis, Structure#Biological, organisation, met ...

beneath the algal floats near the surface, using its large

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

s to spot

prey Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not ki ...

. It possibly immigrated from the

Paleo-Tethys Ocean The Paleo-Tethys or Palaeo-Tethys Ocean was an ocean located along the northern margin of the paleocontinent Gondwana that started to open during the Middle Cambrian, grew throughout the Paleozoic, and finally closed during the Late Triassic; ex ...

Sources

* Mark-Kurik, E & Carls, P. 2002. ''A Long-snouted Late Eifelian Arthrodire from Aragón (Spain)''. Revista Española de Paleontología, Madrid, pp. 117–135. {{Taxonbar, from=Q5045284 Placoderms of Europe Fossil taxa described in 2002 Enigmatic arthrodire taxa Arthrodire genera Devonian Europe Eifelian life Devonian fish of Europe Devonian placoderms