PACHYOSTEOMORPHI STENSIÖ, 1944, Stensio, 1944

Carr, Robert K. & Hlavin, William J., 2010, Two new species of Dunkleosteus Lehman, 1956, from the Ohio Shale Formation (USA, Famennian) and the Kettle Point Formation (Canada, Upper Devonian), and a cladistic analysis of the Eubrachythoraci (Placodermi, Arthrodira), Zoological Journal of the Linnean Society 159 (1), pp. 195-222: 212

publication ID

http://doi.org/ 10.1111/j.1096-3642.2009.00578.x

persistent identifier

http://treatment.plazi.org/id/2B52681A-FFBF-FFAE-FEFB-FCEF1363B9CD

treatment provided by

Carolina

scientific name

PACHYOSTEOMORPHI STENSIÖ, 1944
status

 

PACHYOSTEOMORPHI STENSIÖ, 1944  

(Suborder Brachythoraci Gross 1932   , in part; suborder Pachyosteina Stensiö 1944   ; suborder Pachyosteomorphi Stensiö 1944   , in part; Pachyosteomorphi Stensiö 1959   ; order Pachyosteida Obruchev 1964   ; suborder Pachyostei Stensiö 1969   )

The Pachyosteomorphi   (node 5; Fig. 9 View Figure 9 ) are a subclade within the Eubrachythoraci (node 4; Fig. 9 View Figure 9 ), and are sister group to the Coccosteomorphi (node 6; Fig. 9 View Figure 9 ). The following families are included here within the Eubrachythoraci Pachyosteomorphi   : Braunosteidae Stensiö, 1959 (included within the Selenosteidae sensu Denison, 1978   ), Bungartiidae Denison, 1975   , Dinichthyidae   , Dunkleosteidae   , Hadrosteidae Gross, 1932   , Leiosteidae Stensiö, 1963   , Mylostomatidae Woodward, 1891   , Panxiosteidae Wang, 1979   , Selenosteidae   (including the Pachyosteidae Gross, 1932   and the Rhinosteidae Stensiö, 1963   ), Titanichthyidae Dean, 1901b   , Trematosteidae Gross, 1932   , Brachydeiridae Gross, 1932   , Leptosteidae Jaekel, 1911   , and Rachiosteidae Stensiö, 1963   (the inclusion of the latter three families is tentatively based on their opened pectoral fenestra in some members of each family, and the probable loss of the spinal plate); and Coccosteomorphi – Camuropiscidae   , Coccosteidae Traquair, 1888   , Incisoscutidae Denison, 1984   , Torosteidae Gardiner & Miles, 1990 (with the latter included within the Plourdosteidae   by Gardiner & Miles, 1994; Long 1995).

The various definitions of the Pachyosteomorphi   result in the confusion of group membership. Stensiö (1944) first defined the Pachyosteomorphi   as all the non-coccosteomorph Brachythoraci   . He did not provide a clear diagnosis for the group, but did include some forms like Di. herzeri   , the Pachy- osteidae, and the Trematosteidae   . Stensiö (1959) later included the Pachyosteomorphi   in the Aspinothoracidi, based on the pectoral fin and endoskeletal girdle structure alone. To account for the presence of a dermal plate connecting the lateral and ventral thoracic armour in Dunkleosteus, Stensiö   coined the term ‘pseudospinal’ for what he thought was an independently derived spinal plate. As pointed out by Miles & Dennis (1979), Stensiö assumed the absence of spinals to be primitive. It then appears clear that, based on a parsimony argument, the ‘pseudospinal’ of Stensiö represents a homologous and primitive feature of the Pachyosteomorphi   ( Mark-Kurik, 1963; Heintz, 1968; Carr, 1991). The reduction of the spinal plate associated with the loss of a spinal pit is a synapomorphy for the Pachyosteomorphi   ( Gardiner & Miles, 1990: their character 22.32, although the latter character is equivocal because of missing data; in the present analysis, character 46). Unambiguous synapomorphies for the Eubrachythoraci in the present study include: (1) the development of a continuous occipital thickening (character 12, state 1); (2) the subequal length of the preorbital plate relative to the central plate (character 15, state 0); (3) a reduction in the ossification of the palatoquadrate forming two ossifications (autopalatine and quadrate; character 57, state 1); (4) the loss of the groove for the postorbital sensory line on the suborbital plate (character 81, state 0); and (5) the confluence of the postorbital branch of the infraorbital sensory line and supraoral sensory line grooves (character 83, state 1). The Pachyosteomorphi   are characterized by: (1) the increased length of the central–nuchal plate contact (character 21, state 1); (2) the presence of a short and broad median dorsal plate (character 36, state 0); (3) the development of a lateral contact between the suborbital and preorbital plates (character 54, state 1); (4) the presence of posterolateral processes on the parasphenoid (character 72, state 1); and (5) the loss of the groove for the ventrolateral sensory line on the anterior lateral plate (character 77, state 0).

Order

Pachyosteida

Loc

PACHYOSTEOMORPHI STENSIÖ, 1944

Carr, Robert K. & Hlavin, William J. 2010
2010
Loc

Incisoscutidae

Denison 1984
1984
Loc

Panxiosteidae

Wang 1979
1979
Loc

Camuropiscidae

Dennis & Miles 1979
1979
Loc

Selenosteidae

sensu Denison 1978
1978
Loc

Selenosteidae

sensu Denison 1978
1978
Loc

Bungartiidae

Denison 1975
1975
Loc

Dunkleosteus, Stensiö

, Stensio 1969
1969
Loc

Dunkleosteidae

Stensio 1963
1963
Loc

Leiosteidae Stensiö, 1963

Stensio 1963
1963
Loc

Rhinosteidae Stensiö, 1963

Stensio 1963
1963
Loc

Rachiosteidae Stensiö, 1963

Stensio 1963
1963
Loc

Pachyosteomorphi

Stensio 1959
1959
Loc

Pachyosteomorphi

Stensio 1959
1959
Loc

Pachyosteomorphi

Stensio 1959
1959
Loc

Pachyosteomorphi

Stensio 1959
1959
Loc

Pachyosteomorphi

Stensio 1959
1959
Loc

Pachyosteomorphi

Stensio 1959
1959
Loc

Pachyosteomorphi

Stensio 1959
1959
Loc

Pachyosteomorphi

Stensio 1959
1959
Loc

Hadrosteidae

Gross 1932
1932
Loc

Pachyosteidae

Gross 1932
1932
Loc

Trematosteidae

Gross 1932
1932
Loc

Brachydeiridae

Gross 1932
1932
Loc

Brachythoraci

Gross 1932
1932
Loc

Trematosteidae

Gross 1932
1932
Loc

Leptosteidae

Jaekel 1911
1911
Loc

Titanichthyidae

Dean 1901
1901
Loc

Mylostomatidae

Woodward 1891
1891
Loc

Coccosteidae

Traquair 1888
1888
Loc

Dinichthyidae

Newberry 1885
1885
Loc

Di. herzeri

Newberry 1868
1868