Ptychopariida

Triarthrus eatoni

Order Ptychopariida / Suborder Olenina / Family Olenidae

Katian (Late Ordovician)USA, Canada
Triarthrus eatoni — photo 1
Photo 1 · Neotype (USA; Ludvigsen et al. 1983) The famous "egg-bearing" ventrally compressed specimen (USA; Hegna et al., 2017) Restoration (Cisne, 1973) (USA; housed in the Yingliang Stone (USA; Guodong) (USA; Yuzhao) (USA; Mr. Heiyanquan) Natural History Museum) Complete dorsal exoskeleton (USA; Y.W)
Triarthrus eatoni — photo 2
Photo 2 · Neotype (USA; Ludvigsen et al. 1983) The famous "egg-bearing" ventrally compressed specimen (USA; Hegna et al., 2017) Restoration (Cisne, 1973) (USA; housed in the Yingliang Stone (USA; Guodong) (USA; Yuzhao) (USA; Mr. Heiyanquan) Natural History Museum) Complete dorsal exoskeleton (USA; Y.W)
Triarthrus eatoni — photo 3
Photo 3 · Neotype (USA; Ludvigsen et al. 1983) The famous "egg-bearing" ventrally compressed specimen (USA; Hegna et al., 2017) Restoration (Cisne, 1973) (USA; housed in the Yingliang Stone (USA; Guodong) (USA; Yuzhao) (USA; Mr. Heiyanquan) Natural History Museum) Complete dorsal exoskeleton (USA; Y.W)
Triarthrus eatoni — photo 4
Photo 4 · Neotype (USA; Ludvigsen et al. 1983) The famous "egg-bearing" ventrally compressed specimen (USA; Hegna et al., 2017) Restoration (Cisne, 1973) (USA; housed in the Yingliang Stone (USA; Guodong) (USA; Yuzhao) (USA; Mr. Heiyanquan) Natural History Museum) Complete dorsal exoskeleton (USA; Y.W)
Triarthrus eatoni — photo 5
Photo 5 · Neotype (USA; Ludvigsen et al. 1983) The famous "egg-bearing" ventrally compressed specimen (USA; Hegna et al., 2017) Restoration (Cisne, 1973) (USA; housed in the Yingliang Stone (USA; Guodong) (USA; Yuzhao) (USA; Mr. Heiyanquan) Natural History Museum) Complete dorsal exoskeleton (USA; Y.W)
Triarthrus eatoni — photo 6
Photo 6 · Neotype (USA; Ludvigsen et al. 1983) The famous "egg-bearing" ventrally compressed specimen (USA; Hegna et al., 2017) Restoration (Cisne, 1973) (USA; housed in the Yingliang Stone (USA; Guodong) (USA; Yuzhao) (USA; Mr. Heiyanquan) Natural History Museum) Complete dorsal exoskeleton (USA; Y.W)
Triarthrus eatoni — photo 7
Photo 7 · Neotype (USA; Ludvigsen et al. 1983) The famous "egg-bearing" ventrally compressed specimen (USA; Hegna et al., 2017) Restoration (Cisne, 1973) (USA; housed in the Yingliang Stone (USA; Guodong) (USA; Yuzhao) (USA; Mr. Heiyanquan) Natural History Museum) Complete dorsal exoskeleton (USA; Y.W)
Triarthrus eatoni — photo 8
Photo 8 · Neotype (USA; Ludvigsen et al. 1983) The famous "egg-bearing" ventrally compressed specimen (USA; Hegna et al., 2017) Restoration (Cisne, 1973) (USA; housed in the Yingliang Stone (USA; Guodong) (USA; Yuzhao) (USA; Mr. Heiyanquan) Natural History Museum) Complete dorsal exoskeleton (USA; Y.W)
Triarthrus eatoni — photo 9
Photo 9 · Neotype (USA; Ludvigsen et al. 1983) The famous "egg-bearing" ventrally compressed specimen (USA; Hegna et al., 2017) Restoration (Cisne, 1973) (USA; housed in the Yingliang Stone (USA; Guodong) (USA; Yuzhao) (USA; Mr. Heiyanquan) Natural History Museum) Complete dorsal exoskeleton (USA; Y.W)
Classification
Order Ptychopariida / Suborder Olenina / Family Olenidae
Genus
Triarthrus Green, 1832
Genus author
Green J.
Genus etymology
tri-, three; arthr-, Greek, joint
Species
T. eatoni Hall, 1838
Species author
Hall J.
Species etymology
Eaton, a surname
Age
Katian (Late Ordovician)
Distribution
USA, Canada
Synonyms
Triarthrus becki macastyensis
Diagnosis
Dorsal shield long-ovate. Glabella subrectangular with four pairs of glabellar furrows, the anterior two pairs long and deep, the posterior two pairs short and shallow; preglabellar field short; palpebral lobes medium-long; eye ridges short and small. Thorax of 14 segments; axis slightly wider than pleurae; pleural furrows deep, pleural spines short. Pygidium small, broad-elliptical.
Remarks
The pyritised specimens of Triarthrus eatoni have made a great contribution to understanding the soft-body structures of polymerid trilobites.