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Odontochitina octopus
Odontochitina octopus Núñez-Betelu and Hills, 1998, p.928–929, pl.1, figs.1–6.
Holotype: Núñez-Betelu and Hills, 1998, pl.1, fig.5.
Age: late Coniacian?
Original decscription (Núñez-Betelu and Hills, 1998)
Diagnosis. Species of Odontochitina with four finger-like extensions on the apical horn, and two extensions on each of the postcingular and antapical horns. These extensions correspond to the partial separation of the paraplates that form the horns. Horns are essentially coplanar either primarily or due to secondary compression.
Etymology Origin of species name: from Latin octopus, which means having eight legs.
Type specimen Holotype, sample GF 52 1/3 (coordinates: l.67x, 8.99y), collected at Glacier Fiord (southern Axel Heiberg Island; 78°38'N, 89°55'W), Pl. 1, fig. 5. Illustrated specimens other than the holotype should be considered as paratypes (Pl. 1, figs. 1-4 and 6).
Type locality: Kanguk Formation, Glacier Fiord section, Glacier Fiord (78°38'N, 89°55'W).
Type stratum: 189 m above the base of the Kanguk Formation, southeastern Axel Heiberg Island, Canadian Arctic
Archipelago.
Description
Cyst type: cavate to cornucavate.
Shape: ceratioid, with quadruple finger-like tapered terminations on the apical horn and two terminations on each of
the postcingular and antapical horns. Endocyst ovoidal. The horn subdivisions are coplanar, with pointed tips.
Wall relationships: pericoel developed only in horns, otherwise the periphragm and the endophragm are usually compressed. However, in some specimens a narrow pericoel separates the periphragm and the endophragm.
Wall features: endophragm smooth and moderately thick. Periphragm punctuate and thin, often folded. Edge of apical terminations finely ragged to slightly dentate. No parasutural features observed.
Paratabulation: not indicated.
Archeopyle: apical, type tA, archeopyle suture smooth except for a sulcal notch; the apical horn primarily forms the
perioperculum, the endoperculum does not protrude into the apical horn; opercula always free.
Paracingulum: not indicated.
Parasulcus: not indicated, except for sulcal notch.
Dimensions of holotype: pericyst (without operculum), width 64 μm, length 160 μm. Endocyst (without operculum),
width 62 μm, length 72 μm. Perioperculum, width at the base 29 μm, length 105 μm. Apical finger-like terminations,
width at the base 6 (8) 11 μm, length 80 (85) 88 μm. Postcingular horn, width at the base 28 μm, length 64 μm. Postcingular finger-like terminations, width at the base 4 and 6 μm, length 30 and 33 μm. Antapical horn, width at the base 32 μm, length 88 μm. Antapical finger-like terminations, width at the base 6 and 14 μm, length 48 and 50 μm. Size range: pericyst (without operculum), width 52 (60) 70 μm, length 135 (156) 164 μm. Endocyst (without
operculum), width 52 (59) 68 μm, length 56 (74) 79 μm. Perioperculum, width at the base 36 (38) 46 μm, length 106
(124) 146 μm. Apical-like terminations, width at the base 6(8.5) 12 μm, length 69 (83) 98 μm. Postcingular horns,
width at the base 16 (28) 39 μm, length 68 (86) 94 μm. Postcingular finger-like terminations, width at the base 4 (5)
7 μm, length 24 (31) 36 μm. Antapical horns, width at the base 18 (32) 38 μm, length 48 (68) 82 μm. Antapical finger-like terminations, width at the base 6 (9) 15 μm, length 36 (46) 54 μm. Sixteen specimens measured.
Remarks: this species differs from other species of Odontochitina in having a quadruple finger-like termination
of the apical horn and double finger-like terminations of the postcingular and antapical horns. Odontochitina octopus
probably evolved from 0 . costata because lineations and perforations occur along the horns of the latter in a pattern
that may have led to the splitting of the horns in the former. In some studies (i.e., Alberti 1961), some specimens of
0. costata have horns with connected elongate perforations, as well as ribs. These ribs appear to represent paraplate boundaries and divide the apical horn into four paraplates. In the Family Ceratiaceae four plates usually form the apical horn, whereas two plates are involved in the postcingular and antapical horns (Happach-Kasan 1982). Each one of these plates seems to have developed into a single horn in 0 . octopus. There is a gradation in the development of the ribs and perforations on 0. costata, from a restricted occurrence onthe proximal portion of the horns to an unrestricted distribution (Norvick and Burger 1975, p. 90, Fig. 16, and p. 91, Fig. 17). This gradation is also observed in specimens of 0. costata from the Kanguk Formation. Perforations and ribs are absent from the central body or the endophragm of O. costata. Perforations and ribs are absent from the entire ectophragm of 0. octopus and only denticulate edges occur on the horns. In summary, the genus Odontochitina includes cysts with
single long, apical, antapical, and probably postcingular horns (Stover and Evitt 1978). This is a common feature of
all species of this genus. However, the cyst of 0. octopus possesses finger-like terminations on the horns, namely quadruple apical, double postcingular, and double antapical terminations. All the other features of 0. octopus conform with the definition of the genus and it is also likely that 0. octopus evolved from 0. costata.
Age: late Coniacian, based on associated S. depressus (Hills et al. 1994).
Holotype: Núñez-Betelu and Hills, 1998, pl.1, fig.5.
Age: late Coniacian?
Original decscription (Núñez-Betelu and Hills, 1998)
Diagnosis. Species of Odontochitina with four finger-like extensions on the apical horn, and two extensions on each of the postcingular and antapical horns. These extensions correspond to the partial separation of the paraplates that form the horns. Horns are essentially coplanar either primarily or due to secondary compression.
Etymology Origin of species name: from Latin octopus, which means having eight legs.
Type specimen Holotype, sample GF 52 1/3 (coordinates: l.67x, 8.99y), collected at Glacier Fiord (southern Axel Heiberg Island; 78°38'N, 89°55'W), Pl. 1, fig. 5. Illustrated specimens other than the holotype should be considered as paratypes (Pl. 1, figs. 1-4 and 6).
Type locality: Kanguk Formation, Glacier Fiord section, Glacier Fiord (78°38'N, 89°55'W).
Type stratum: 189 m above the base of the Kanguk Formation, southeastern Axel Heiberg Island, Canadian Arctic
Archipelago.
Description
Cyst type: cavate to cornucavate.
Shape: ceratioid, with quadruple finger-like tapered terminations on the apical horn and two terminations on each of
the postcingular and antapical horns. Endocyst ovoidal. The horn subdivisions are coplanar, with pointed tips.
Wall relationships: pericoel developed only in horns, otherwise the periphragm and the endophragm are usually compressed. However, in some specimens a narrow pericoel separates the periphragm and the endophragm.
Wall features: endophragm smooth and moderately thick. Periphragm punctuate and thin, often folded. Edge of apical terminations finely ragged to slightly dentate. No parasutural features observed.
Paratabulation: not indicated.
Archeopyle: apical, type tA, archeopyle suture smooth except for a sulcal notch; the apical horn primarily forms the
perioperculum, the endoperculum does not protrude into the apical horn; opercula always free.
Paracingulum: not indicated.
Parasulcus: not indicated, except for sulcal notch.
Dimensions of holotype: pericyst (without operculum), width 64 μm, length 160 μm. Endocyst (without operculum),
width 62 μm, length 72 μm. Perioperculum, width at the base 29 μm, length 105 μm. Apical finger-like terminations,
width at the base 6 (8) 11 μm, length 80 (85) 88 μm. Postcingular horn, width at the base 28 μm, length 64 μm. Postcingular finger-like terminations, width at the base 4 and 6 μm, length 30 and 33 μm. Antapical horn, width at the base 32 μm, length 88 μm. Antapical finger-like terminations, width at the base 6 and 14 μm, length 48 and 50 μm. Size range: pericyst (without operculum), width 52 (60) 70 μm, length 135 (156) 164 μm. Endocyst (without
operculum), width 52 (59) 68 μm, length 56 (74) 79 μm. Perioperculum, width at the base 36 (38) 46 μm, length 106
(124) 146 μm. Apical-like terminations, width at the base 6(8.5) 12 μm, length 69 (83) 98 μm. Postcingular horns,
width at the base 16 (28) 39 μm, length 68 (86) 94 μm. Postcingular finger-like terminations, width at the base 4 (5)
7 μm, length 24 (31) 36 μm. Antapical horns, width at the base 18 (32) 38 μm, length 48 (68) 82 μm. Antapical finger-like terminations, width at the base 6 (9) 15 μm, length 36 (46) 54 μm. Sixteen specimens measured.
Remarks: this species differs from other species of Odontochitina in having a quadruple finger-like termination
of the apical horn and double finger-like terminations of the postcingular and antapical horns. Odontochitina octopus
probably evolved from 0 . costata because lineations and perforations occur along the horns of the latter in a pattern
that may have led to the splitting of the horns in the former. In some studies (i.e., Alberti 1961), some specimens of
0. costata have horns with connected elongate perforations, as well as ribs. These ribs appear to represent paraplate boundaries and divide the apical horn into four paraplates. In the Family Ceratiaceae four plates usually form the apical horn, whereas two plates are involved in the postcingular and antapical horns (Happach-Kasan 1982). Each one of these plates seems to have developed into a single horn in 0 . octopus. There is a gradation in the development of the ribs and perforations on 0. costata, from a restricted occurrence onthe proximal portion of the horns to an unrestricted distribution (Norvick and Burger 1975, p. 90, Fig. 16, and p. 91, Fig. 17). This gradation is also observed in specimens of 0. costata from the Kanguk Formation. Perforations and ribs are absent from the central body or the endophragm of O. costata. Perforations and ribs are absent from the entire ectophragm of 0. octopus and only denticulate edges occur on the horns. In summary, the genus Odontochitina includes cysts with
single long, apical, antapical, and probably postcingular horns (Stover and Evitt 1978). This is a common feature of
all species of this genus. However, the cyst of 0. octopus possesses finger-like terminations on the horns, namely quadruple apical, double postcingular, and double antapical terminations. All the other features of 0. octopus conform with the definition of the genus and it is also likely that 0. octopus evolved from 0. costata.
Age: late Coniacian, based on associated S. depressus (Hills et al. 1994).