Arkell.1956.Jurassic..

548
CORDILLERAS OF NORTH AMERICA
Cardioceratidae. Though we differ in many details we agree that besides
the majority of species clearly indicating both Cordatum and Mariae Zones
of the Lower Oxfordian there are minorities which can only be of the age
of the Lamberti Zone (Upper Callovian) and Plicatilis Zone (Upper
Oxfordian). In the following list the references are to Reeside's plates
and figures.
1. Quenstedtoceras (hamberticerasT) collieri Reeside, i, 1-8.
2. Quenstedtoceras (Eboraciceras) hoveyi Reeside, i, 9-14; ii, 1.
3. Quenstedtoceras (Eboraciceras) tumidum Reeside, iv, 8-10; v, 3-4.
4. Quenstedtoceras (Eboraciceras) subtumidum (W. & H.), iv, 16.
5. Quenstedtoceras (Pavloviceras) latum (Reeside), xx, 7-16.
6. Goliathiceras suspectum (Reeside), iv, 5-7; v, 1-2.
7. Goliathiceras crookense (Reeside), ix, 2-4.
8. Goliathiceras russelli (Reeside), xiii, 2-3; xiv, 3-5.
9. Goliathiceras crassum (Reeside), xii, 3-4; xiii, 1; xiv, 1-2.
10. Goliathiceras albaniense (Reeside), xxiii (non xxiv, 1-2).
11. Cardioceras (Scarburgiceras) americanum Reeside, vi, 15-20.
12. Cardioceras (Scarburgiceras) cordiforme (M. & H.), vii, viii, ix, 1.
13. Cardioceras (Scarburgiceras reesidei Maire, viii, 4-5 only (type).
14. Cardioceras (Scarburgiceras) martini Reeside, ix, 5-8.
15. Cardioceras (Scarburgiceras) schucherti Reeside, xi, 3-5.
16. Cardioceras (Scarburgiceras) wyomingense Reeside, xv, 12-17.
17. Cardioceras (transitional, Scarburgiceras-Cardioceras) auroraense Reeside, x.
18. Cardioceras (Cardioceras) hyatti Reeside, xv, 1-4.
19. Cardioceras (Cardioceras)
x v
distans (Whitfield), xv, 18-24; '-
20. Cardioceras (Cardioceras) lilloetense Reeside, xvii, 20-23.
21. Cardioceras (Scoticardioceras) whitfieldi Reeside, vi, 1 -6.
22. Cardioceras (Scoticardioceras) alaskense Reeside, vi, 7-10.
23. Cardioceras (Scoticardioceras) stillwelli Reeside, vi, 11-14.
24. Cardioceras (Vertebriceras) stantoni Reeside, xv, 5-8.
25. Cardioceras (Vertebriceras) obesum Reeside, xv, 9-11.
26. Cardioceras (Sagitticeras) haresi Reeside, xix, 4-12.
27. Cardioceras (Sagitticeras!) obtusum Reeside, xx, 1-6.
28. Cardioceras (Subvertebriceras) canadense Whiteaves, xvii, 5-11.
29. Cardioceras (Caictoniceras) whiteavesi Reeside, xvii, 1-4.
30. Cardioceras (Maltoniceras) sundancense Reeside, xvii, 12-19.
31. Cardioceras (Maltoniceras) prionodes Crickmay sp., 1936, pis. ii, iii, xviii, 1-3.
32. Cardioceras (subgen. nov.) plattense Reeside, ix, 9-12.
33. Cardioceras (subgen. nov.) bellefourchense Reeside, xi, 1-2; xii, r-2.
34. ? Pachyceras incertum (Reeside), xx, 17-20; xxi; xxii.
Using the numbers in this list for brevity, the age-indications are as
follows:—
1-4 Upper Callovian, Lamberti Zone
5, 14-17 Lower Oxfordian, Mariae Zone
6-13, 18-27 Lower Oxfordian, Cordatum Zone
28-31 Upper Oxfordian, Plicatilis Zone
No doubt future collecting will determine whether four horizons can be
distinguished in the field, or whether all or any combinations of the four
are blended. (Cf. Crickmay, 1936: it is not clear why it is a 'gross error'
(p. 554) to take nos. 2-4 in the above list at their face value.)
In England Scoticardioceras is more characteristic of the Plicatilis
Zone, but the American forms (21-23) are not like the English in ribbing
habit and probably are earlier. Several of the species of Scarburgiceras
are very close to English forms of both Mariae and Cordatum Zones, and
one may be identical (C. reesidei Maire; Arkell, 1946, op. cit., p. 307).
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