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Mellopegma
Taxonomy
Mellopegma was named by Runnegar and Jell (1976) [Sepkoski's age data: Cm Tomm-l Cm uMid-m Sepkoski's reference number: 885,1030].
It was assigned to Procarinariidae by Runnegar and Jell (1976); to Mellopegmidae by Missarzhevsky (1989); to Helcionellidae by Landing et al. (2002); to Helcionelloida by Sepkoski (2002); to Stenothecinae by Parkhaev (2002), Parkhaev (2004), Bouchet et al. (2005); and to Stenothecidae by Runnegar and Jell (1980), Vendrasco et al. (2011).
It was assigned to Procarinariidae by Runnegar and Jell (1976); to Mellopegmidae by Missarzhevsky (1989); to Helcionellidae by Landing et al. (2002); to Helcionelloida by Sepkoski (2002); to Stenothecinae by Parkhaev (2002), Parkhaev (2004), Bouchet et al. (2005); and to Stenothecidae by Runnegar and Jell (1980), Vendrasco et al. (2011).
Species
Synonymy list
| Year | Name and author |
|---|---|
| 1976 | Mellopegma Runnegar and Jell |
| 1980 | Mellopegma Runnegar and Jell p. 111 |
| 1989 | Mellopegma Missarzhevsky p. 179 |
| 2002 | Mellopegma Landing et al. p. 298 |
| 2002 | Mellopegma Parkhaev p. 36 |
| 2002 | Mellopegma Sepkoski |
| 2004 | Mellopegma Parkhaev p. 602 |
| 2005 | Mellopegma Bouchet et al. pp. 107, 241 |
| 2011 | Mellopegma Vendrasco et al. pp. 11A:6-7 |
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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.
G. †Mellopegma Runnegar and Jell 1976
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†Mellopegma georginensis Runnegar and Jell 1976
†Mellopegma indecora Rozanov et al. 1969
†Mellopegma schizocheras Vendrasco et al. 2011
†Mellopegma uslonica Parkhaev 2004
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| M. J. Vendrasco et al. 2011 | Stenothecid molluscs with elongate shells (typical l/w >4) that lack a zygion and possess a strongly curved ventral margin.
Laterally compressed, elongate univalves with strongly curved ventral (aperture) margin. Slight coiling (less than half a whorl; cladistic character 4, state 0; Appendix 1), with gently convex supra-apical dorsal margin and concave subapical margin that ends in a flat to downward-sloping shelf. Shell microstructure of outer layer prismatic and inner layer calcitic semi-nacre (character 17, state 1). Tubercles (granules) occur sporadically on surface of internal moulds, revealing shell pores that extend through most or all of the thickness of the shell (character 14, state 1). Inner sculpture of gentle to prominent comarginal ridges (character 6, state 1). |
Measurements
No measurements are available
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| Source: f = family, c = class | |||||
| Reference: Hendy et al. 2009 | |||||
Collections (28 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Placentian | USA (Massachusetts) | M. sp. (56833 56836) | |
| Meishucunian | China (Yunnan) | M. sp. (108309) | |
| Tommotian | Russian Federation (Yakutia) | Anabarella indecora (45850 45851 45852) | |
| Tommotian | Russian Federation (Khabarovsk Krai) | M. sp. (50420) | |
| Tommotian | Russian Federation (Yakutiya) | Anabarella indecora (80796 96251 96391 96394) | |
| Branchian | United Kingdom (England) | Anabarella indecora (79931 79939) | |
| Botomian | Russian Federation (Chitinskaya oblast) | M. uslonica (49383 49387) | |
| Botomian | Russian Federation (Siberia) | M. uslonicum (174258) | |
| Dyeran | Canada (Quebec) | M. georginensis (78755) | |
| Dyeran | USA (New York) | Stenotheca drepanoides (78762 78767) | |
| Dyeran | Greenland | M. sp. (225140) | |
| Ordian | Australia (New South Wales) | M. sp. (56811) | |
| Templetonian | Australia (Queensland) | M. georginensis (70046) | |
| Middle Cambrian | Canada (British Columbia) | M. georginense (171309) | |
| Floran | Australia (Queensland) | M. georginensis (56809 93407 93409) M. georginensis, M. schizocheras (93420) | |
| Marjumian | USA (Utah) | M. georginensis (230682) |