Platanites raynoldsii (NEWBERRY) Manchester, 2014

Manchester, Steven R., 2014, Revisions To Roland Brown’S North American Paleocene Flora, Acta Musei Nationalis Pragae Series B 70 (3 - 4), pp. 153-210 : 163-166

Platanites raynoldsii (NEWBERRY) comb. nov.

Text-figs 6.1–6.4

1868 Platanus raynoldsi NEWBERRY, Lyceum Nat. Hist. New York Ann., 9, p. 69 (basionym); 1898 Platanus raynoldsi NEWBERRY, U. S. Geol. Surv. Monogr. , 35, p. 109, pl. 35.

1993 Platanites canadensis MCIVER et BASINGER , p. 38, pl. 23, pl. 24, figs 1–4.

2008 Ettingshausenia raynoldsii (NEWBERRY) MOISEEVA , p. 324 [excluding all of the Asian figured specimens].

McIver and Basinger (1993) illustrated a beautifully complete compound leaf of Platanites from the Paleocene Ravenscrag Formation of southern Saskatchewan, Canada, showing a pair of lateral elliptical leaves attached to the “petiole” of a leaf matching architecturally to the holotype of Platanus raynoldsii (reillustrated here, Text-fig. 6.2 ). Hence, the petiole of P. raynoldsii is actually the rachis of a compound leaf. Because Newberry’s species has long been considered to be a simple leaf, as expected for extant Platanus, McIver and Basinger (1993) considered the the Ravenscrag material to be distinct and described it as a new species, Platanites canadensis . They used the generic name based on similar compound platanaceous leaves from Scotland ( P. hebridicus FORBES ; Crane et al. 1988).

Close comparison between Newberry’s holotype specimen of P. raynoldsii ( Text-fig. 6.1 ) and the holotype of P. canadensis ( Text-fig. 6.2 ) indicates that they are architecturally identical, leading to the conclusion that they are conspecific. Other compound leaves of P. raynoldsii have been recovered occasionally in the Late Cretaceous and Paleocene of North America (e.g., specimens figured by Knowlton 1930, pl 45, fig. 10 as Negundo decurrens LESQUEREUX , and by Ellis et al. 2003, fig. 9a as Platanites marginata (LESQUEREUX) K. JOHNSON , but usually the petiole/rachis lacks lateral leaflets, giving appearance that “they leaves” were simple. We do not know whether this is due to deciduousness and/or damage prior to deposition, or if P. raynoldsii might have been variable, producing both simple and compound leaves on the same individual (perhaps a difference between seedling and mature leaves, for example). Nevertheless, the tendency to produce compound leaves distinguishes this species from all extant species of Platanus , and justifies its assignment to the extinct genus, Platanites .

Prior to the realization that this species represents a compound-leaved plant, Brown (1962), adopted the name Platanus raynoldsii (and included Newberry’s P. haydeni in synonymy), for most weakly trilobate platanaceous leaves from the Paleocene of the Rocky Mountains and Great Plains region and provided a thorough synonymy of earlier published specimens from the works of Newberry, Lesquereux, Ward and Knowlton. The same epithet was applied to similar laminae from the late Cretaceous and Paleocene of Far Eastern Russia ( Krassilov 1976). Based mainly on her investigations of the far eastern Russian material, Moiseeva (2008) established a new combination, Ettingshausenia raynoldsii , for the species, applying the fossil-genus name Ettingshausenia STIEHLER (1857) . However, Ettingshausenia is believed to be a simpleleaved genus. It is possible that the genus Ettingshausenia is appropriately applied to theAsian fossils, but a different specific epithet is needed from that applied to the North American species considered here. It is not appropriate to use the name Ettingshausenia in the case of the type material of P. raynoldsii NEWBERRY , which conforms instead to Platanites FORBES.

Figures

Text-fig. 6. Platanaceae 1–3. Platanites raynoldsii (NEWBERRY) comb. nov. 1. Holotype of Platanus raynoldsii NEWBERRY (1868, 1898), Banks of the Yellowstone River, Montana, USNM 7000. 2. Holotype of Platanites canadensis MCIVER et BASINGER (1993), here treated as synonym of P. raynoldsii, showing clearly the position of the lateral leaflets, US 3-66, Ravenscrag Formation, Saskatchewan, Canada. 3. Specimen from Yellowstone Bridge, Miles City, Montana. UF19021-39390. 4. Detail from fig. 2. Scale bars 5 cm.