# Doryaspis

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***Doryaspis*** is an [extinct](/source/Extinction) [genus](/source/Genus) of armored [jawless fish](/source/Jawless_fish) belonging to the [order](/source/Taxonomic_order) [Pteraspidiformes](/source/Pteraspidiformes). It contains five [species](/source/Species), all of which are exclusively known from what is now the [island](/source/Island) of [Spitsbergen](/source/Spitsbergen) in the [Svalbard](/source/Svalbard) [archipelago](/source/Archipelago) of [Norway](/source/Norway). The genus lived during the [Pragian](/source/Pragian) to [Emsian](/source/Emsian) [ages](/source/Geologic_age) of the [Early](/source/Early_Devonian) [Devonian](/source/Devonian) [period](/source/Geologic_period). *Doryaspis* is distinguished from other pteraspidiforms by several unusual features, most notably its narrow, outward-pointing cornual [plates](/source/Plate_(anatomy)) and a long, pointed projection near its [mouth](/source/Mouth) known as a pseudorostrum.

## Discovery and research history

[Fossils](/source/Fossil) of what would later be described as *Doryaspis* were first discovered by [Alfred Gabriel Nathorst](/source/Alfred_Gabriel_Nathorst) during a [Swedish](/source/Sweden) expedition to Spitsbergen in 1882. The fossils consisted of several disarticulated [ventral](/source/Ventral) armor plates recovered from the [Wood Bay Formation](/source/Wood_Bay_Formation).[1][2] Two years later, [zoologist](/source/Zoologist) [Edwin Ray Lankester](/source/Ray_Lankester) identified these as the [bony](/source/Bone) [cephalic](/source/Cephalic) (head) shield of a [cephalaspid](/source/Cephalaspidae) [fish](/source/Fish), a group that pteraspidomorphs were, at the time, thought to belong to. He noted that the fossils were similar in form to those of *Scaphaspis lloydii* from [England](/source/England) and established a new species for the specimens, *Scaphaspis nathorstii*.[1][3] In the year 1900, *Scaphaspis* was deemed synonymous with *[Pteraspis](/source/Pteraspis)*, and [Arthur Smith Woodward](/source/Arthur_Smith_Woodward) reassigned these fossils under the name *Pteraspis nathorsti*.[4][5] [Johan Aschehoug Kiær](/source/Johan_Aschehoug_Ki%C3%A6r) later studied the material and recognized it as representing a [taxon](/source/Taxon) distinct from *Pteraspis*, establishing the genus *Doryaspis* to refer to the plates.[6] However, before Kiær's work could be published, [paleontologist](/source/Paleontologist) [Anatol Heintz](/source/Anatol_Heintz) used the name "Dyreaspis" for the same specimens in 1934. This name never received an official diagnosis and is considered a [*nomen nudum*](/source/Nomen_nudum).[7] Kiær passed away before his study could be published, but his work was eventually utilized by [geologist](/source/Geologist) [Errol Ivor White](/source/Errol_White) who recognized the genus *Doryaspis* in 1935.[6][3]

In 1967, it was discovered that the name *Doryaspis* had already been used for a genus of [beetles](/source/Beetle) described in 1835. According to the [International Code of Zoological Nomenclature](/source/International_Code_of_Zoological_Nomenclature), no two taxa may share the same name, and the earlier named taxon has priority. To resolve this conflict, paleontologist [Natascha Heintz](/source/Natascha_Heintz) created the genus *Lyktaspis* to replace the name established by Kiær. However, in 1970, it was determined by Robert Denison that the beetle genus should be considered a *nomen nudum* and was therefore invalid. As a result, *Doryaspis* continues to be used as the valid name for the fish genus.[6][8][9]

## Description

### Headshield

Like other [heterostracans](/source/Heterostraci), the front half of *Doryaspis* was covered in several stiff [plates](/source/Plate_(anatomy)) of [bony](/source/Bone) armor collectively known as a headshield. The headshield had a broad, flat topside and a rounded underside. The two largest plates, the [dorsal](/source/Dorsal_(anatomy)) and [ventral](/source/Ventral) plates,[note 1] were ornamented with a radiating pattern of concentric ridges which bore small [tubercles](/source/Tubercle) arranged in a [chevron](/source/Chevron_(insignia)) pattern. Additionally, both plates were covered in a system of [sensory](/source/Perception) canals.[2][3][6] In front of the dorsal plate were two orbital plates that formed a [crescent](/source/Crescent) shape wrapping around the dorsal plate. Each plate had protrusions that projected the [eye](/source/Eye) opening outwards. In front of the orbital plates was a small, [semicircular](/source/Semicircular) [rostral](/source/Rostral_(anatomical_term)) plate. Between the rostral plate and the dorsal plate was a tiny [pineal](/source/Pineal_gland) plate. Some species possessed a small [spine](/source/Spine_(zoology)) that projected upward on the back of the dorsal plate, however, this spine is not considered the same structure as the "dorsal spine" in other pteraspids. The underside of the animal was formed by three plates: the ventral plate and a pair of orogonal plates near the mouth.[3][6][note 2]

On either side of the headshield were two [wing](/source/Wing)-like cornual plates. The cornual plates were a shared feature of most heterostracans[10][11][12] but were exceptionally long and narrow in *Doryaspis*. The cornual plates had a similar tubercle ornamentation to the dorsal and ventral plates. In some species, the tubercles along the forward-facing edge of the cornual plates were modified into hook-shaped denticles. The shape and size of the cornual plates in *Doryaspis* varied greatly between species.[3][6]

#### Mouth

As an [agnathan](/source/Agnatha), *Doryaspis* possessed no [jaws](/source/Jaw). The mouth opening sat between the orogonal plates and the rostral plate and faced upward rather than forward or downward, an unusual orientation among pteraspidomorphs.[3] Projecting forward from between the orogonal plates was a pointed, [blade](/source/Blade)-like appendage called the pseudorostrum.[3][8] It has been suggested that the pseudorostrum may be a greatly enlarged and modified middlemost oral plate, though this has not been conclusively established.[3][13] In some species, the edges of the pseudorostrum bore small hook-shaped denticles similar to those on the cornual plates.[3][6] The lower edge of the mouth also bore two [triangular](/source/Triangular) “lateral oral plates” which flanked the pseudorostrum on either side.[3] These plates were not capable of opening and closing the mouth,[3] unlike the oral plates in other pteraspidomorphs.[2][14]

### Trunk and tail

Behind the headshield, the body of *Doryaspis* was covered in large, overlapping [scales](/source/Fish_scale) arranged in six rows. Along the top and bottom midlines of the body ran a row of teardrop-shaped "ridge scales". On each side of the body between these ridge scales were two rows of [rhombus](/source/Rhombus)-shaped "flank scales". Each ridge scale overlapped two to four of the upper flank scales beside it, which in turn overlapped the lower flank scales, which were themselves overlapped by the ventral ridge scales. Between fifteen and twenty flank scales could be present in each row along the length of the trunk. This relatively simple scale arrangement, with only two rows of flank scales on each side, is considered more [primitive](/source/Primitive_(phylogenetics)) than that of most other pteraspidiforms, which typically possessed many more rows of smaller scales.[3]

The [tail fin](/source/Caudal_fin) is known only from a single specimen of *D. nathorsti*. It consisted of three lobes with a thin membrane of tiny scales connecting them. The fin was likely [homocercal](/source/Homocercal), meaning that the upper and lower lobes were roughly equal in size.[3][15]

## Species

The genus *Doryaspis* comprises five [species](/source/Species), all recovered from the [Wood Bay Formation](/source/Wood_Bay_Formation) of [Spitsbergen](/source/Spitsbergen). The [morphology](/source/Morphology_(biology)) varies considerably between species. An [undescribed](/source/Undescribed_taxon) sixth species is also known, recovered in association with *D. nathorsti*. It is poorly preserved, but was larger than *D. nathorsti*, making it the largest known representative of the genus.[3]

The various species of *Doryaspis*, alongside other genera, have been utilized as [guide fossils](/source/Guide_fossils) to identify the [biotic divisions](/source/Biozone) of the Wood Bay Formation. This [formation](/source/Formation_(geology)) has been [stratigraphically](/source/Stratigraphy) described under two regional frameworks. The [Woodfjorden](/source/Woodfjorden) area of northwestern Spitsbergen uses four [[ faunal divisions (from oldest to youngest: Sigurdfjellet, Kapp Kjeldsen, Keltiefjellet, and Stjørdalen). The [Dicksonfjorden](/source/Dicksonfjorden)-[Austfjorden](/source/Austfjorden_(Svalbard)) area of southeastern Spitsbergen instead uses three [lithostratigraphic](/source/Lithostratigraphy) [members](/source/Member_(geology)) (Austfjorden, Dicksonfjorden, and Verdalen) which correspond to the Sigurdfjellet and Kapp Kjeldsen, Keltiefjellet, and Stjørdalen divisions respectively.[16][17]

### *Doryaspis nathorsti*

*Doryaspis nathorsti* is the [type species](/source/Type_species) of the genus, described by Lankester in 1884 on the basis of material collected by Nathorst.[1] It is the largest described species of *Doryaspis*, with a maximum dorsal plate length of 70 mm (2.8 in).[6] *D. nathorsti* is distinguished by large cornual plates that extended sideways from the body and curved downwards and slightly forward near the tips. Both the front edge of the cornual plates and the edges of the pseudorostrum bore denticles. Between the plates around the gill opening were four or five small "accessory plates", a feature not observed in other species of the genus.[3] *D. nathorsti* is present throughout the upper Kapp Kjeldsen division and the entire Keltiefjellet division in the Woodfjorden area and the majority of the Dicksonfjorden Member in the Dicksonfjorden-Austfjorden area.[17][16]

### *Doryaspis lyktensis*

*Doryaspis lyktensis* was originally described in 1960 by Natascha Heintz as a possible species of *Pteraspis*, *P.? lyktensis*.[18] Four years later, [Dmitry Obruchev](/source/Dmitry_Obruchev) placed the species in its own genus, *Grumantaspis*. In 1984, *Grumantaspis* was deemed synonymous with *Doryaspis* by Blieck.[6] The species is known from a single slab bearing three more or less complete dorsal plates, four more or less complete ventral plates, and several fragments, leaving much of its biology unknown.[18][19] These dorsal plates measured approximately 18 to 20 mm (0.71 to 0.79 in) in length. *D. lyktensis* did not possess a spine on the dorsal plate. *D. lyktensis* is present in the uppermost Kapp Kjeldsen division in the Woodfjorden area[18] and most of the Dicksonfjorden Member in the Dicksonfjorden-Austfjorden area.[17]

A fossil recovered from the [Ben Nevis Formation](/source/Ben_Nevis_Formation) bears close resemblance to *D. lyktensis*. This formation directly underlies the Wood Bay Formation and is [Lochkovian](/source/Lochkovian) in age, which would make this the oldest known specimen of *Doryaspis* and the first known outside of the Wood Bay Formation. However, this fossil has not yet been confidently referred to the genus or species.[17][16]

### *Doryaspis minor*

*Doryaspis minor* has a very similar taxonomic history to that of *D. lyktensis*. It was described in 1960 by Natascha Heintz as *Pteraspis? minor*, moved to its own genus *Ennosveaspis* by [Erik Stensiö](/source/Erik_Stensi%C3%B6) in 1964, and subsequently synonymized with *Doryaspis* by Blieck in 1984.[6][18] *D. minor* is known from only four plates total, comprising one nearly complete dorsal plate measuring 14 mm (0.55 in) in length, one additional fragmentary dorsal plate, and two fragmentary ventral plates, making it the most poorly documented and smallest known species of *Doryaspis*.[18][19] Like *D. lyktensis*, this species lacked a dorsal spine on the dorsal plate. The distribution of the species is poorly understood, though the known material likely comes from the Stjørdalen division in the Woodfjorden area.[17][18]

### *Doryaspis arctica*

*Doryaspis arctica* was described in 2002 by Vincent Noël Pernègre. The [specific name](/source/Specific_name_(zoology)), *arctica*, is in reference to the species' fossils originating from the [arctic](/source/Arctic) archipelago of Svalbard.[3] This species' dorsal plate was up to 60 mm (2.4 in) long.[6] In this species, the cornual plates were narrow, lacked denticles, and were angled slightly backwards without any noticeable curve.[6][3] *D. arctica* is present throughout the entire Sigurdfjellet division and most of the Kapp Kjeldsen division in the Woodfjorden area.[17][16]

### *Doryaspis groenhorgensis*

*Doryaspis groenhorgensis* was described in 2005 by Pernègre based on fossils from Grønhorgdalen in Spitsbergen. The dorsal plate of this species was up to 35 mm (1.4 in) long. The ventral plate of *D. groenhorgensis* comes to a triangular point near the front of the animal, where in other species the plate is rounded. The cornual plates were the smallest known of any species and possessed characteristics intermediate between those of *D. nathorsti* and *D. arctica*: they were pointed backwards and lacked denticles as in *D. arctica*, but had a slight forward curve at the tip as in *D. nathorsti*. The pseudorostrum was relatively wide and bore denticles, though these were smaller ornamental tubercles instead of the well-developed hooks characteristic of *D. nathorsti*. The portion of the pseudorostrum that connected to the rest of the headshield was also a shallow V-shape rather than the broader U-shape seen in both *D. nathorsti* and *D. arctica*.[6] This species is found throughout the majority of the Austfjorden Member in the Dicksonfjorden-Austfjorden area.[17][16]

## Paleobiology

Like other pteraspidomorphs, *Doryaspis* lacked any true [paired fins](/source/Paired_fins) and would have relied primarily on its caudal fin to propel itself through its [environment](/source/Natural_environment). The large, [wing](/source/Wing)-like cornual plates are thought to have functioned as [lifting](/source/Lift_(force)) surfaces while [swimming](/source/Fish_locomotion), serving a purpose similar to the [pectoral fins](/source/Pectoral_fins) of other fish.[6] The branchial ([gill](/source/Gill)) openings were located slightly in front of the cornual plates. It has been proposed that these openings may have been used by pteraspidomorphs to stabilize and control their movement by adjusting the flow of ejected water under the cornual plates. A 2024 study by Héctor Botella and colleagues tested life-sized [3D printed](/source/3D_printed) models of *D. nathorsti* in a [water tunnel](/source/Water_tunnel_(hydrodynamic)). It was found that the headshield functioned like a [delta wing](/source/Delta_wing) and formed a pair of stable, counter-rotating [leading-edge vortices](/source/Vortex_lift) over the top surface during forward motion which generated upward lift.[10]

The exact lifestyle of *Doryaspis* is not fully understood, owing to its highly unusual [anatomy](/source/Anatomy) among pteraspidiforms.[6] Two competing [hypotheses](/source/Hypothesis) have been proposed: that *Doryaspis* was a [pelagic](/source/Pelagic_fish), open-water animal living high in the [water column](/source/Water_column), or that *Doryaspis* was a [benthic](/source/Benthic_fish) animal living partially buried in the sediment.[6]

The pelagic hypothesis argues that the lift generated by the cornual plates, the homocercal caudal fin,[15] and the [hydrodynamic](/source/Hydrodynamic) properties of the headshield would have been advantageous for open-water swimming.[6][19] The upward-facing mouth, flat dorsal plate, and lack of a large dorsal spine may indicate that *Doryaspis* fed at or near the surface of the water.[6][13][19] Additionally, the pseudorostrum is proposed to have been used to skim the surface of the water for food like [plankton](/source/Plankton) and direct it into the mouth.[6][19]

The benthic hypothesis argues that the flat dorsal plate could instead indicate that *Doryaspis* lived half-buried in the sediment of its environment. It is proposed that long cornual plates and pseudorostrum would have kept the animal stabilized and from sinking further into the substrate. In this scenario, the upturned mouth would have faced away from the ground and could passively [filter feed](/source/Filter_feeder) organic matter, which was abundant near the substrate. However, the branchial openings would have been susceptible to being blocked by sediment in this mode of life, which would have [suffocated](/source/Suffocated) the animal. It has been proposed that *Doryaspis* could have possessed a [soft tissue](/source/Soft_tissue) covering over the branchial openings in life in order to keep out sediment.[6]

In 2005, Pernègre concluded that the available evidence slightly favored the pelagic interpretation, though neither hypothesis could be definitively ruled out.[6] Some subsequent studies have erroneously cited this conclusion as supporting the burrowing behavior.[20][21] The 2024 hydrodynamics study by Botella found that *D. nathorsti* performed better near the substrate compared to the more [streamlined](/source/Streamlined) pteraspidiform *[Panamintaspis](/source/Panamintaspis) snowi*, which performed well in open water. This was interpreted as indicating a benthic lifestyle for *D. nathorsti* with the capacity for short bursts into the water column.[10]

## Paleoecology

*Doryaspis* is only definitively known from the [Wood Bay Formation](/source/Wood_Bay_Formation)[3][6] and is present throughout all four biostratigraphic divisions.[16][17] It is the most abundant heterostracan in the formation.[3][6]

The [paleoenvironment](/source/Paleoenvironment) of the Wood Bay Formation is not well understood.[17] [Sedimentological](/source/Sedimentological) evidence from the formation indicates a terrestrial setting of [floodplains](/source/Floodplain), [rivers](/source/River), and [lakes](/source/Lake) in a [semi-arid](/source/Semi-arid_climate), monsoonal [climate](/source/Climate).[22][23][24] However, certain fossils recovered from the formation are traditionally associated with [marine](/source/Marine_ecosystem) environments,[25] leading to some authors to argue that the Wood Bay Formation may instead represent a [coastal](/source/Coast) environment such as an [estuary](/source/Estuary) or [fjord](/source/Fjord).[17][26]

*Doryaspis* coexisted with a diverse assemblage of early [vertebrates](/source/Vertebrate). Other heterostracans, [osteostracans](/source/Osteostraci), and [thelodonts](/source/Thelodonti) are all known from the formation, as are [jawed fish](/source/Jawed_fish) including [placoderms](/source/Placoderm), [acanthodians](/source/Acanthodians), and [lobe-finned fish](/source/Lobe-finned_fish).[16]

## See also

- *[Pycnosteus](/source/Pycnosteus)*, a [psammosteid](/source/Psammosteida) heterostracan with similar wing-like cornual plates[27]
- *[Alienacanthus](/source/Alienacanthus)*, an [arthrodire](/source/Arthrodira) [placoderm](/source/Placoderm) with an extended, tooth-covered lower jaw that has been compared to *Doryaspis nathorsti*'s denticled pseudorostrum[28]

## Notes

1. Also called the "dorsal disc" and "ventral disc"

1. The orogonal plates are equivalent to the "postoral plates" in other pteraspids

## References

1. Lankester, Edwin Ray (1884). ["Report on fragments of fossil fishes from the Palaeozoic strata of Spitsbergen"](https://books.google.com/books?id=3brFugNA2tYC). *Kongliga Svenska Vetenskaps-Akademiens Handlingar*

1. White, Errol Ivor (1935). ["The Ostracoderm Pteraspis Kner and the Relationships of the Agnathous Vertebrates"](https://www.jstor.org/stable/92279). *Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences*. **225** (527): 381–457. [Bibcode:1935RSPTB.225..381W](https://ui.adsabs.harvard.edu/abs/1935RSPTB.225..381W). [doi:10.1098/rstb.1935.0015](https://doi.org/10.1098/rstb.1935.0015). [ISSN 0080-4622](https://www.worldcat.org/issn/0080-4622). [JSTOR 92279](https://www.jstor.org/stable/92279)

1. Pernègre, Vincent Noel (2002). ["The Genus Doryaspis White (Heterostraci) from the Lower Devonian of Vestspitsbergen, Svalbard"](https://www.jstor.org/stable/4524274). *Journal of Vertebrate Paleontology*. **22** (4): 735–746. [doi:10.1671/0272-4634(2002)022\[0735:TGDWHF](https://doi.org/10.1671/0272-4634(2002)022%5B0735:TGDWHF%5D2.0.CO;2)2.0.CO;2]. [ISSN 0272-4634](https://www.worldcat.org/issn/0272-4634). [JSTOR 4524274](https://www.jstor.org/stable/4524274). – via [JSTOR](/source/JSTOR)

1. Woodward, A. Smith (July 1891). ["I.— The Devonian fish-fauna of Spitzbergen"](https://www.tandfonline.com/doi/full/10.1080/00222939109460384). *Annals and Magazine of Natural History*. **8** (43): 1–15. [doi:10.1080/00222939109460384](https://doi.org/10.1080/00222939109460384). [ISSN 0374-5481](https://www.worldcat.org/issn/0374-5481)

1. Woodward, Arthur Smith (1900). ["Notes on fossil fish-remains collected in Spitsbergen by the Swedish Arctic expedition, 1898"](https://www.biodiversitylibrary.org/item/49831). *Kongliga Svenska Ventenskaps-Akademiens Handlingar*. **25** (4): 230–239.

1. Pernègre, Vincent Noël (2005-03-01). ["Description d'une nouvelle espèce et analyse morpho-fonctionnelle du genre Doryaspis White (Heterostraci) du Dévonien du Spitsberg"](https://www.sciencedirect.com/science/article/pii/S0016699505000239) [Description of a new species and morpho-functional analysis of the genus Doryaspis White (Heterostraci) from the Devonian of Spitsbergen] (in French). *Geobios*. **38** (2): 257–268. [Bibcode:2005Geobi..38..257P](https://ui.adsabs.harvard.edu/abs/2005Geobi..38..257P). [doi:10.1016/j.geobios.2003.10.005](https://doi.org/10.1016/j.geobios.2003.10.005). [ISSN 0016-6995](https://www.worldcat.org/issn/0016-6995)

1. Heintz, Anatol (July–August 1934). ["Hvordan fiskene har lært sig å svømme"](https://marcus.uib.no/instance/issue/ubb-tskr-naturen-1934-07) [HOW THE FISHES LEARNED TO SWIM] (in Norwegian). *Naturen*. **58** (7–8): 230–256. – via MARCUS.

1. Denison, Robert H. & Denison, Robert H. (1970). [*Revised classification of Pteraspididae with description of new forms from Wyoming*](https://www.biodiversitylibrary.org/bibliography/3330). Chicago: Field Museum of Natural History. [doi:10.5962/bhl.title.3330](https://doi.org/10.5962/bhl.title.3330)

1. Blieck, A. & Heintz, N. (1979-01-01). ["The heterostracan faunas in the Red Bay Group (Lower Devonian) of Spitsbergen and their biostratigraphical significance; a review including new data"](https://pubs.geoscienceworld.org/sgf/bsgf/article/S7-XXI/2/169/111076/The-heterostracan-faunas-in-the-Red-Bay-Group). *Bulletin de la Société Géologique de France*. **S7-XXI** (2): 169–181. [doi:10.2113/gssgfbull.S7-XXI.2.169](https://doi.org/10.2113/gssgfbull.S7-XXI.2.169). [ISSN 1777-5817](https://www.worldcat.org/issn/1777-5817)

1. Botella, Héctor; Fariña, Richard A.; Huera-Huarte, Francisco (2024-09-16). "Delta wing design in earliest nektonic vertebrates". *Communications Biology*. **7** (1): 1153. [doi:10.1038/s42003-024-06837-8](https://doi.org/10.1038/s42003-024-06837-8). [ISSN 2399-3642](https://www.worldcat.org/issn/2399-3642). [PMC 11405518](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11405518). [PMID 39284892](https://pubmed.ncbi.nlm.nih.gov/39284892)

1. Randle, Emma & Sansom, Robert S. (2017-07-03). ["Exploring phylogenetic relationships of Pteraspidiformes heterostracans (stem-gnathostomes) using continuous and discrete characters"](https://www.tandfonline.com/doi/full/10.1080/14772019.2016.1208293). *Journal of Systematic Palaeontology*. **15** (7): 583–599. [Bibcode:2017JSPal..15..583R](https://ui.adsabs.harvard.edu/abs/2017JSPal..15..583R). [doi:10.1080/14772019.2016.1208293](https://doi.org/10.1080/14772019.2016.1208293). [ISSN 1477-2019](https://www.worldcat.org/issn/1477-2019)

1. Sanchez-Sanchez, Vicente; Sanisidro, Oscar; Ferrón, Humberto G. (May 2025). ["Functional aspects of the headshield processes in ostracoderms"](https://www.cambridge.org/core/journals/paleobiology/article/functional-aspects-of-the-headshield-processes-in-ostracoderms/F7B833F1AD34CA60BEAAB7174AF6F15F). *Paleobiology*. **51** (2): 310–322. [Bibcode:2025Pbio...51..310S](https://ui.adsabs.harvard.edu/abs/2025Pbio...51..310S). [doi:10.1017/pab.2025.5](https://doi.org/10.1017/pab.2025.5). [hdl:10550/114362](https://hdl.handle.net/10550/114362). [ISSN 0094-8373](https://www.worldcat.org/issn/0094-8373)

1. Tarlo, Lambert (1962). ["The classification and evolution of the Heterostraci"](https://www.app.pan.pl/archive/published/app07/app07-249.pdf). *Acta Palaeontologica Polonica*. **7** (1–2): 249–290.

1. Dearden, Richard P.; Jones, Andy S.; Giles, Sam; Lanzetti, Agnese; Grohganz, Madleen; Johanson, Zerina; Lautenschlager, Stephan; Randle, Emma; Donoghue, Philip C. J.; Sansom, Ivan J. (2024-03-27). "The three-dimensionally articulated oral apparatus of a Devonian heterostracan sheds light on feeding in Palaeozoic jawless fishes". *Proceedings of the Royal Society B: Biological Sciences*. **291** (2019). [doi:10.1098/rspb.2023.2258](https://doi.org/10.1098/rspb.2023.2258). [ISSN 0962-8452](https://www.worldcat.org/issn/0962-8452). [PMC 10965320](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10965320). [PMID 38531402](https://pubmed.ncbi.nlm.nih.gov/38531402)

1. Giammona, Francesca F (2021-09-08). ["Form and Function of the Caudal Fin Throughout the Phylogeny of Fishes"](https://academic.oup.com/icb/article/61/2/550/6296422). *Integrative and Comparative Biology*. **61** (2): 550–572. [doi:10.1093/icb/icab127](https://doi.org/10.1093/icb/icab127). [ISSN 1540-7063](https://www.worldcat.org/issn/1540-7063). [PMID 34114010](https://pubmed.ncbi.nlm.nih.gov/34114010)

1. Blieck, Alain; Goujet, Daniel; Janvier, Philippe (January 1987). ["The vertebrate stratigraphy of the Lower Devonian (Red Bay Group and Wood Bay Formation) of Spitsbergen"](https://www.researchgate.net/publication/290391865). *Modern Geology*. **11**: 197–217. – via ResearchGate.

1. Pernègre, V.N. & Blieck, A. (2016). ["A revised heterostracan-based ichthyostratigraphy of the Wood Bay Formation (Lower Devonian, Spitsbergen), and correlation with Russian Arctic archipelagos"](https://www.researchgate.net/publication/299477690). *Geodiversitas*. **38** (1): 5–20. [Bibcode:2016Geodv..38....5P](https://ui.adsabs.harvard.edu/abs/2016Geodv..38....5P). [doi:10.5252/g2016n1a1](https://doi.org/10.5252/g2016n1a1). [S2CID 55307211](https://api.semanticscholar.org/CorpusID:55307211)

1. Heintz, Natascha (1960). ["The Downtonian and Devonian vertebrates of Spitsbergen. X, Two new species of the genus Pteraspis from the Wood Bay series in Spitsbergen"](https://hdl.handle.net/11250/173630). *Norsk Polarinstitutt Skrifter*. **117**. [hdl:11250/173630](https://hdl.handle.net/11250/173630). – via Norwegian Research Information Repository.

1. Blieck, Alain (January 1984). [*Les Héterostracés Pteraspidiformes, Agnathes du Silurien-Dévonien du Continent Nord-Atlantique et des blocs avoisinants: Révision systématique, phylogénie, biostratigraphie, biogéographie*](https://www.researchgate.net/publication/262764499) (in French). Cahiers de paléontologie. Section vertébrés.

1. Gai, Zhikun; Lu, Liwu; Zhao, Wenjin; Zhu, Min (2018-09-19). "New polybranchiaspiform fishes (Agnatha: Galeaspida) from the Middle Palaeozoic of China and their ecomorphological implications". *PLOS ONE*. **13** (9). [Bibcode:2018PLoSO..1302217G](https://ui.adsabs.harvard.edu/abs/2018PLoSO..1302217G). [doi:10.1371/journal.pone.0202217](https://doi.org/10.1371/journal.pone.0202217). [ISSN 1932-6203](https://www.worldcat.org/issn/1932-6203). [PMC 6145596](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6145596). [PMID 30231026](https://pubmed.ncbi.nlm.nih.gov/30231026)

1. Blieck, Alain (2017-09-01). "Heterostracan vertebrates and the Great Eodevonian Biodiversification Event—an essay". *Palaeobiodiversity and Palaeoenvironments*. **97** (3): 375–390. [Bibcode:2017PdPe...97..375B](https://ui.adsabs.harvard.edu/abs/2017PdPe...97..375B). [doi:10.1007/s12549-016-0260-1](https://doi.org/10.1007/s12549-016-0260-1). [ISSN 1867-1608](https://www.worldcat.org/issn/1867-1608)

1. Blomeier, Dierk; Wisshak, Max; Dallmann, Winfried; Volohonsky, Eden; Freiwald, André (2003-01-01). ["Facies analysis of the old Red Sandstone of Spitsbergen (Wood Bay Formation): Reconstruction of the depositional environments and implications of basin development"](https://doi.org/10.1007/s10347-003-0030-1). *Facies*. **49** (1): 151–174. [Bibcode:2003Faci...49..151B](https://ui.adsabs.harvard.edu/abs/2003Faci...49..151B). [doi:10.1007/s10347-003-0030-1](https://doi.org/10.1007/s10347-003-0030-1). [ISSN 1612-4820](https://www.worldcat.org/issn/1612-4820)

1. Blomeier, Dierk; Wisshak, Max; Joachimski, Michael; Freiwald, André; Volohonsky, Eden (January 2003). ["Calcareous, alluvial and lacustrine deposits in the Old Red Sandstone of central north Spitsbergen (Wood Bay Formation, Early Devonian)"](https://www.researchgate.net/publication/240612660). *[Norsk Geologisk Tidsskrift](/source/Norwegian_Journal_of_Geology)*. – via [ResearchGate](/source/ResearchGate)

1. Friend, P. F. & Moody-Stuart, M. (May 1970). ["Carbonate deposition on the river floodplains of the Wood Bay Formation (Devonian) of Spitsbergen"](https://www.cambridge.org/core/journals/geological-magazine/article/abs/carbonate-deposition-on-the-river-floodplains-of-the-wood-bay-formation-devonian-of-spitsbergen/B64583B90E0681057A31788620EED97C). *Geological Magazine*. **107** (3): 181–195. [Bibcode:1970GeoM..107..181F](https://ui.adsabs.harvard.edu/abs/1970GeoM..107..181F). [doi:10.1017/S0016756800055655](https://doi.org/10.1017/S0016756800055655). [ISSN 1469-5081](https://www.worldcat.org/issn/1469-5081)

1. Goujet, Daniel (1985). ["Des Lingula fossiles, indicateurs de modifications de l'environnement dans un gisement du Dévonien inférieur du Spitsberg."](http://paleopolis.rediris.es/Phoronida/EMIG/REPRINTS/95.pdf). *[Comptes Rendus de l'Académie des Sciences](/source/Comptes_Rendus_de_l'Acad%C3%A9mie_des_Sciences)*

1. Wisshak, Max; Volohonsky, Eden; Seilacher, Adolf; Freiwald, André (June 2004). ["A trace fossil assemblage from fluvial Old Red deposits (Wood Bay Formation; Lower to Middle Devonian) of NW-Spitsbergen, Svalbard"](https://www.scup.com/doi/10.1080/00241160410005763). *Lethaia*. **37** (2): 149–163. [Bibcode:2004Letha..37..149W](https://ui.adsabs.harvard.edu/abs/2004Letha..37..149W). [doi:10.1080/00241160410005763](https://doi.org/10.1080/00241160410005763). [ISSN 0024-1164](https://www.worldcat.org/issn/0024-1164)

1. Moloshnikov, Sergey (2001). ["New Data on Pycnosteus palaeformis Preobrazhensky (Heterostraci, Psammosteiformes) from the Arukula Deposits of the Leningrad Region"](https://www.researchgate.net/publication/270876124). *Paleontologicheskii Zhurnal*. **35** (4). – via [ResearchGate](/source/ResearchGate)

1. Jobbins, Melina; Martin Rücklin, Martin; Sánchez Villagra, Marcelo R.; Lelièvre, Hervé; Grogan, Eileen; Szrek, Piotr; Klug, Christian (31 January 2024). "Extreme lower jaw elongation in a placoderm reflects high disparity and modularity in early vertebrate evolution". *Royal Society Open Science*. **11** (1). [Bibcode:2024RSOS...1131747J](https://ui.adsabs.harvard.edu/abs/2024RSOS...1131747J). [doi:10.1098/rsos.231747](https://doi.org/10.1098/rsos.231747). [PMC 10827443](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10827443). [PMID 38298398](https://pubmed.ncbi.nlm.nih.gov/38298398). [S2CID 267331593](https://api.semanticscholar.org/CorpusID:267331593)

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Adapted from the Wikipedia article [Doryaspis](https://en.wikipedia.org/wiki/Doryaspis) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Doryaspis?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.