Palæos:		Unit 40: Pteraspidomorphi
The Vertebrates		520: Amphiaspidida (2)

Pteraspidomorphi: Amphiaspidida: Amphiaspidida (2)

The three families of amphiaspids

CRANIATA
|--CONODONTA
`--+--THELODONTI
   |
   Pteraspidomorphi
   |--Arandaspida
   `--Heterostracomorphi
      |--Astraspidae
      `--Heterostraci
         |--Cyathaspidiformes
         |  |--Cyathaspidida
         |  `--Amphiaspidida
         |     |--Amphiaspidoidei
         |     `--+--Hibernaspidoidei  
         |        `--Siberiaspidoidei
         `--Pteraspidiformes
            |--Pteraspididae
            `--Psammosteida
               |--Drepanaspis
               `--Psammosteidae

Taxa on This Page

1. Amphiaspidoidei X
2. Hibernaspidoidei X
3. Siberiaspidoidei X

Amphiaspidoidei: Amphiaspis, Angraspis, Edaphaspis, Gabreyaspis, Kureykaspis, Olbiaspis, Pelaspis, Prosarctaspis, Tareyaspis

Range: Early Devonian (Lochkovian to earliest Emsian) of Siberia [N86]

Phylogeny: Amphiaspidida:: (Hibernaspidoidei + Siberiaspidoidei) + *.

Characters:  All plates fused, with occasional exception of the posterior ventral area [N86]; anterior margin rounded or straight [N86]; mouth ventral, terminal or subterminal [N86]; oral tubes absent [N86]; orbits at anterodorsal margin of the armor [N86]; praespiracular apertures are present adjacent to orbit [N86]; lateral edges smooth or with "teeth" [N86]; sensory line furrows usually short, slightly curved in the longitudinal lines frequently found? in the alar regions [N86]; sensory line system confined to pit lines, without channels [S64]; ventromedially, sensory lines ‘V’-shaped, with anterior commisures forming rectangular figure [N86]; commisures are positioned laterally relative to the longitudinal ventral lines [N86]; pattern of sensory lines unique [S64]; sculpturing present as flattened ridges with smooth edges (in older forms) [N86]; or with tubercles and grebeshkis [N86] [S64]; some species have tesserae [N86].  

Note: Stensiö wrote when only three amphiaspids were known.  His comments refer here only to Amphiaspis.  

Image: Angaraspis from [N86].

References: Novitskaya (1986) [N86]; Stensiö (1964) [S64].  ATW030508. 

Hibernaspidoidei: Aphataspis, Eglonaspis, Empedaspis, Gerronaspis, Hibernaspis, Lecanaspis, Pelurgaspis, Putoranaspis

Range: Early Devonian (Pragian to Emsian) of Siberia [N86], including Lochkovian of Severnaya Zemlya [B+02].

Phylogeny: Amphiaspidida::: Siberiaspidoidei + *.

Characters: All plates are fused, with the occasional exception of the posterior ventral area [N86]; anterior margin usually extended as an oral tube (absent in primitive forms) [N86]; mouth ventral and subterminal, or terminal in forms having an oral tube [N86]; orbits on lateral margin of armor, or laterally on dorsal surface, or towards the distal end of an oral tube, or absent [N86]; praespiraculum absent [N86]; lateral edges with teeth (except Putoranaspis) [N86]; sensory sulci are present and, probably in some species, sensory channels (huh?) [N86]; supraorbital sensory line are not always present [N86]; longitudinal pairs of sulci (medial and lateral) form, with cross-commisures, rectangular figures [N86]; cross commisures usually lateral relative to ventral longitudinal furrows (??) [N86]; sculpturing looks like wide strips with smooth edges [N86]; some species with large, hexagonal tubercles [N86] [S64]; between strips are sometimes interspersed separate rounded tubercles [N86]; tesserae are absent [N86].   

Note: Stensiö wrote when only three amphiaspids were known.  His comments refer here only to Eglonaspis and Hibernaspis.  

Image: Hibernaspis adapted from [N86].  Note that the large oval laterally is not an orbit, but the branchial opening.  The orbits are two tiny dots on the dorsal surface of the rostrum.

Links: IX Capitolo - I Primi Pesci.  

References: Blieck et al. (2002) [B+02]; Novitskaya (1986) [N86]; Stensiö (1964) [S64].  ATW040726.

Siberiaspidoidei: Argyraspis, Dotaspis, Litotaspis, Siberiaspis, Tuxeraspis.  

Range: Early Devonian (Pragian) of Siberia.  

Phylogeny: Amphiaspidida::: Hibernaspidoidei + *.

Characters: All plates of the shield are fused [N86]; anterior margin rounded, straight, or superficially excavated [N86]; oral tubes absent [N86]; mouth ventral, terminal or subterminal [N86]; orbits laterodorsal or on lateral edges of armor; [N86]; praespiracula absent [N86]; lateral edges, where known, without jagged projections [N86]; sensory line system present as sulci and channels (the last are definitively known in the Siberiaspididae) [N86]; arrangement of the sensory sulci as in Amphiaspidoidei; sculpturing present as smooth platens or tubercles with smooth or jagged edges (i.e. grebeshkis) [N86]; tesserae absent [N86].

References: Novitskaya (1986) [N86].  ATW030509. 

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