|
Reference
|
| Title: |
Report on Referred Fossils
,
1960
(11/07)
|
|
This report supplements those of W.A. Oliver, Jr. (dated 8/18/59) and Serge Mamay (dated 6/1/59). Additional brachiopods and molluscs in collections 58(?)AMr387 permit a refinement of the age designation of that collection. It is either of latest Middle Devonian or earliest Late Devonian age. Collection 58AL88 contains linguloid brachiopods, perhaps assignable to the genus Barroisella, that suggest a Middle or Late Devonian age. E&R report prepared by J.T. Dutro, Jr., in consultation with E.L. Yochelson |
| Report by: |
J. Thomas Dutro
, Jr.
,
Ellis L. Yochelson
|
| Referred by: |
E. H. Lathram
|
|
|
|
| | Age: | Middle Devonian-Late Devonian (Middle Devonian or Late Devonian) |
|
|
|
|
|
|
| Comment: | Collection contains, in addition to the Psilophyton-type and "Hostimella"-type plants, linguloid brachiopods (cf. Barroisella) and pelecypod fragments, indet. The fossil assemblage, along with the presence of iron pyrite in the black silty matrix, suggests a reducing environment in a near-shore depositional setting. This could reflect estuarine or lagoonal conditions. |
|
|
| Title: |
Report on Referred Fossils
,
1959
(06/01)
|
|
|
| Report by: |
Sergius H. Mamay
|
| Referred by: |
E. H. Lathram
|
|
|
|
| | Age: | Silurian-Late Devonian (middle Silurian - Late Devonian) |
|
|
|
|
|
|
| Comment: | Plant material in this collection is identical with, and no more helpful stratigraphically, than that contained in the collection I previously reported on (my report of 8/6/58; shipment A-58-5). The plants are again of the Psilophyton type, with naked dichotomous axes, some with evidence of spiny surfaces, and with the recurved "Hostimella tips. Age range of this type of material is Middle Silurian to Upper Devonian. The collection also contains a few linguloid brachiopods which will be reported on later. |
|
|
| Title: |
Report on Referred Fossils
,
1958
(08/06)
|
|
|
| Report by: |
Sergius H. Mamay
|
| Referred by: |
E. H. Lathram
|
|
|
|
| | Age: | Silurian-Late Devonian (middle Silurian - Late Devonian) |
|
|
|
|
|
|
| Comment: | Collection 58AL88 (Lathram, 1958) contains abundant, fragmentary fossils that cannot be regarded as graptolites, but almost certainly are the remains of primitive woody plants. Three of our Lower Paleozoic paleozoologists concur in the opinion that such features of these fossils as (a) surface texture, (b) original bulk of the axes, as evidenced by their thickness in compression, and (c) method of branching are not in harmony with features of known graptolites. They are, instead, strongly reminescent of psilophytalean plants. The compressed axes display sufficient thickness to indicate that they originally were solid cylindrical structures. Many of them contain particles of coalified material, and some of these show longitudinal striations that suggest their origin from a woody tissue. The surfaces of some fragments also show faint but regular patterns suggestive of the epidermal layer of a plant. Still other fragments have conical, thick-based spinose processes, projecting at right angles to the parent axis. Branching of the axes is by slightly unequal dichotomy at a narrow angle; two successive dichotomies are shown in one fragment. A few examples of what seem to be dichotmomous termini with slender recurved tips were noted. Although preservation of the material is not good enough for a positive generic identification, all the features noted above conform pretty well with Psilophyton Dawson; the recurved branch termini resemble the structures commonly referred to the "genus" Hostimella, which may actually belong to several natural genera of psilophytes. Psilophyton is most characteristic of Lower Devonian rocks, but the psilophytalean complex is known to range from the Middle Silurian through the Middle Devonian, with a few doubtful occurrences in the Upper Devonian. One example has been reported from the European Namurian, but I am skeptical of its validity. Since a positive generic identification is not permitted by the material, the best I can do in the way of an age determination would be to guess that Lower or Middle Devonian age is indicated, on the basis of resemblances of your specimens to Psilophyton. However, I must emphasize the possibility that these sediments are as old as Middle Silurian or as young as Upper Devonian. In view of their importance to your interpretations I strongly urge that a more generous sample of this material be collected and submitted to us for examination. Your material is being retained for the P&S collections. |
|