Ceratobairdia wordensis ( Hamilton, 1942 )

Tarnac, Anaëlle, Forel, Marie-Béatrice, Nestell, Galina, Nestell, Merlynd & Crasquin, Sylvie, 2021, Middle Permian ostracods (Crustacea) from the Guadalupe Mountains, West Texas, USA, European Journal of Taxonomy 770, pp. 1-60 : 38-40

publication ID

https://doi.org/ 10.5852/ejt.2021.770.1499

publication LSID

lsid:zoobank.org:pub:33F92DB8-3122-4F8E-995B-DBF260B3E390

DOI

https://doi.org/10.5281/zenodo.5560041

persistent identifier

https://treatment.plazi.org/id/21095E52-CF5F-C33A-FDB8-53B66356EBF8

treatment provided by

Felipe

scientific name

Ceratobairdia wordensis ( Hamilton, 1942 )
status

 

Ceratobairdia wordensis ( Hamilton, 1942) View in CoL

Figs 9K–R View Fig , 10

Bairdia wordensis Hamilton, 1942: 716 View in CoL , pl. 110 fig. 4.

Ceratobairdia wordensis View in CoL – Sohn 1954: 5; 1960: 69, pl. 4 figs 8–17.

Material examined

USA • 1 left valve; Guadalupe Mountains , West Texas, Williams Ranch Member, Cutoff Formation , Quarry section, sample GM1; Roadian, Middle Permian; MNHN.F. F63447 View Materials 1 left valve; same locality as for preceding; Roadian, Middle Permian; MNHN.F. F63448 View Materials 1 left valve; same locality as for preceding; Roadian, Middle Permian; MNHN.F. F63449 View Materials 1 right valve; Guadalupe Mountains , West Texas, ‘ McKittrick Canyon’ Member, Bell Canyon Formation, MKCS1 section, sample 4 (GM5); Capitanian, Middle Permian; MNHN.F. F63450 View Materials 1 right valve; Guadalupe Mountains , West Texas, Williams Ranch Member, Cutoff Formation, Quarry section, sample GM1; Roadian, Middle Permian; MNHN.F. F63497 View Materials 1 right valve;same locality as for preceding; Roadian, Middle Permian; MNHN.F. F63451 View Materials 1 left valve; same locality as for preceding; Roadian, Middle Permian; MNHN.F. F63452 View Materials 1 complete carapace; Guadalupe Mountains , West Texas , ‘ McKittrick Canyon’ Member, Bell Canyon Formation, MKCS1 section, sample 4 (GM5); Capitanian, Middle Permian; MNHN.F. F63453 View Materials 1 broken carapace, 20 left valves; Guadalupe Mountains , West Texas, Williams Ranch Member, Cutoff Formation, Quarry section, samples GM1, GM2, and GM3; Roadian; MNHN.F. F63660 View Materials 3 broken carapaces, 15 left valves; same locality as for preceding; ‘ McKittrick Canyon’ Member , Bell Canyon Formation , MKCS1 section, samples 4 (GM5) and 2 (GM6), Capitanian; Middle Permian; MNHN.F. F63498 View Materials .

Dimensions

L= 727–1450 µm; H= 397–920 µm ( Fig. 10 View Fig , not considering spines).

Occurrence

Glass Mountains, Texas, USA, Roadian, Middle Permian ( Hamilton 1942; Sohn 1954, 1960); samples GM1, GM2, and GM3, Quarry section, Williams Ranch Member, Cutoff Formation, Roadian; samples 4 (GM5) and 2 (GM6), MKCS1 section, ‘McKittrick Canyon’ Member, Bell Canyon Formation, Capitanian; Guadalupe Mountains, West Texas, USA, Middle Permian (this work).

Remarks

Most of the specimens of Ceratobairdia wordensis ( Hamilton, 1942) in the present work occur as isolated valves and LV are relatively easily assigned to this species based on their unique dorsal ornamentation. The identification of RV is more complex and has been possible because of the description provided by Hamilton (1942: 716) of “the centrodorsal portion of the right valve flattens abruptly to hingeline, expressed as a flat terrace in dorsal bi and as a rather prominent ridge in lateral view; […]; the ventral portion of the right valve sharply infolded, forming a sharp downward projecting ridge terminating in mature molds as a backward projecting spine.”

Hamilton (1942: 716) described the dorsal margin of LV of Ceratobairdia wordensis as “usually ornamented by two to seven short strong spines equally spaced and concentrated dorsally on the middle third or more.” The present material provided LV with 4 to 6 spines, but all other characters leave no doubt on the conspecificity of the specimens. Is the number of spines related to ontogeny? Although Hamilton (1942) mentioned 2 to 7 dorsal spines on LV, the unique specimen illustrated displays 6 spines and no discussion is provided on the possible link between size and number of the spines. Conversely, Sohn (1960: pl. 4 figs 12, 14, 17) illustrated specimens with 8 to 10 dorsal spines and at least one of them shows spines organized into 2 overlapping rows. For the present material, the number of spines along the dorsal margin of LV of Ceratobairdia wordensis ranges from 4 to 6 without pattern related to ontogeny ( Fig. 10 View Fig ):

• most of the smallest specimens, assigned to A-2?, are weathered but the two sufficiently well preserved at dorsal margin show 5 spines, the 2 external being ‘embryonic’,

• the only known specimen of A-1? stage displays 4 dorsal spines,

• the adult specimens display from 4 to 6 spines, the external ones being the smallest.

It is worth noting that in A-2? specimens, the external spines are very small and may be overlooked, leading to the wrong identification of only 3 dorsal spines. However, these specimens cannot be confused with Petasobairdia tricornuta Chen in Shi & Chen, 2002 from the Late Permian of South China ( Shi & Chen 2002) which is more elongate, larger, and with only 3 spines for specimens of a size slightly larger than the adults of Ceratobairdia wordensis .

A significant morphological trend is observed in Ceratobairdia wordensis from the Guadalupe Mountains: whereas the majority of specimens have a relatively smooth surface, several show the development of scattered nodules in the dorsal area of their lateral surface ( Fig. 9O–Q View Fig ). This trend culminates in very rare specimens with the entire lateral surface of the valves covered by nodules ( Fig. 9R View Fig ). This nodular surface is reminiscent of Pustulobairdia Sohn, 1960 but all characters of Ceratobairdia wordensis and the morphological trend observed from smooth to nodular leave no doubt that these specimens belong to Ceratobairdia wordensis .

Kingdom

Animalia

Phylum

Arthropoda

Class

Ostracoda

SubClass

Podocopa

Order

Podocopida

SuperFamily

Bairdioidea

Family

Bairdiidae

Genus

Ceratobairdia

Loc

Ceratobairdia wordensis ( Hamilton, 1942 )

Tarnac, Anaëlle, Forel, Marie-Béatrice, Nestell, Galina, Nestell, Merlynd & Crasquin, Sylvie 2021
2021
Loc

Ceratobairdia wordensis

Sohn I. G. 1960: 69
Sohn I. G. 1954: 5
1954
Loc

Bairdia wordensis

Hamilton B. 1942: 716
1942
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