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Sphaerexochus hiratai

Trilobita - Phacopida - Cheiruridae

Taxonomy
Sphaerexochus hiratai was named by Kobayashi and Hamada (1974). Its type specimen is KPFM 1167-1, a cephalon/head (cranidium), and it is a 3D body fossil. Its type locality is Loc. 3. Ys 15. Gomi Quarry, which is in a Ludlow reef, buildup or bioherm reef rocks in the Fukata Formation of Japan.

Sister species lacking formal opinion data

Synonymy list
YearName and author
1964Sphaerexochus hiratai Kobayashi and Hamada pp. 88 - 90 figs. PI. 6, Figs. 6-10; PI. 7, Figs. 1-8; PI. 8, Figs. 1-5, 6, 7; Text-fig. 6F
1974Sphaerexochus hiratai Kobayashi and Hamada pp. 88 - 90
2011Sphaerexochus hiratai Congreve and Lieberman pp. Table S1

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RankNameAuthor
kingdomAnimalia()
Bilateria
EubilateriaAx 1987
Protostomia
EcdysozoaAguinaldo et al. 1997
Panarthropoda
phylumArthropodaLatreille 1829
subphylumArtiopoda(Hou and Bergstrom)
RankNameAuthor
classTrilobitaWalch 1771
orderPhacopidaSalter 1864
suborderCheirurinaHarrington and Leanza 1957
familyCheiruridaeHawle and Corda 1847
subfamilySphaerexochinaeOpik 1937
genusSphaerexochusBeyrich 1845
specieshiratai

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

Sphaerexochus hiratai Kobayashi and Hamada 1974
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Diagnosis
ReferenceDiagnosis
T. Kobayashi and T. Hamada 1964Cephalon semi-circular and strongly vaulted; glabella nearly semi, globular and overhanging in front; basal lobes subcircular, more or less roundly quadrate in outline and completely isolated from the rest of glabella by a profound posterior furrow \vhich turns from lateral to posterior rather abruptly to join an occipital furrow; anterior and middle lateral furrows linear, fairly long and subparallel to posterior furrow; anterior furrow a little shorter than middle one; lateral margin of glabella a little notched at the end of these two furrows; anterior and middle lobes equal in length and shorter than basal lobe; frontal lobe nearly as long as these two lobes; occipital ring narrow, but somewhat thickened mesially, while it narrows laterally behind basal lobes as these lobes are extended backward in comparison with axial part; median tubercle or spine absent on the ring; ,circumglabellar and occipital furrows very strong; the former slanting forward in antero-Iateral part and running below the glabellar protrusion; the furrow provided there with a narrow frontal rim; cheek small and slanting steeply from small eye which is located near middle lobe and posterior lateral furrow of glabella; fixed ,cheek behind eye subtriangular; posterior border and border furrow well pronounced and bent anteriorly at lateral end; no genal spine issuing from this point. Free cheek, hypostoma and thorax unknown.

In pygidium axial lobe which is highly elevated above pleural lobes, composed of an articulating half-ring, two axial rings and a terminal piece in which the third ring is involved; ring furrows separating them all well pronounced; articulating half-ring almost as large and as prominent as the second ring and separated from ;the first ring by a deep furrow in same line with anterior margin of pleural lobes terminal piece nearly half as long as axial lobe, tripartate by Y-shaped ridge; its anterior and lateral sides steeply inclined; third axial ring marked on the piece only by a pair of constrictions from which the terminal piece suddenly narrows back slowly; pleural lobe broader than axial lobe, horizontal on inner side, inclined moderately or rather steeply on outer side, composed of three fiat-topped ribs and ·deep pleural furrows; anterior and lateral margins of the first pleuron geniculated, forming an obtuse angle between these margins and the rib becoming broadest at geniculation; second rib gently arcuate and more or less broadened distally; third rib wide and somewhat lunate; all of these ribs rounded or subangulate at the ends but not protruded into long spines; lateral margin incised at the end of pleural furrows; posterior margin gently sinuate behind axial lobe.
Measurements
No measurements are available
Composition: low Mg calcitec
Composition 2: chitinc
Entire body: yesg
Adult length: 10 to < 100g
Adult width: 10 to < 100g
Spines: minorg
Ontogeny: molting, addition of partsc
Environment: marinec
Locomotion: fast-movingc
Life habit: low-level epifaunalc
Diet: carnivoref
Vision: well-developedg
Created: 2009-06-09 12:26:29
Modified: 2010-01-10 03:55:17
Source: g = genus, f = family, c = class
References: Hendy 2009, Harrington et al. 1959, Aberhan et al. 2004

Age range: Ludlow or 426.70000 to 422.70000 Ma

Collections (2 total)


Time interval Ma Country or state Original ID and collection number
Ludlow426.7 - 422.7Japan (Shikoku) Sphaerexochus hiratai (type locality: 188690)
Ludlow426.7 - 422.7Japan (Skikoku) Sphaerexochus hiratai (188692)