Debeya, Miquel, 1853

Halamski, Adam T., Kvaček, Jiří, Svobodová, Marcela, Durska, Ewa & Heřmanová, Zuzana, 2020, Late Cretaceous mega-, meso-, and microfloras from Lower Silesia, Acta Palaeontologica Polonica 65 (4), pp. 811-878 : 826-829

Debeya group sensu Krassilov et al. (2005)

Remarks.—Similarities among Late Cretaceous and Paleo-

Fig. 8. Fagalean angiosperm Dryophyllum westerhausianum ( Richter, 1904) Halamski and Kvaček comb. nov. from the North Sudetic Basin, Lower → Silesia, Poland, Assemblage 6 (lower–middle Santonian). A. Enlargement of the incomplete leaflet MB.Pb.2008/256 showing venation and serration of the margin, Rakowice Małe. B. Incomplete leaflet MB.Pb.2008/370, Ocice. C. Probable trifoliolate leaf MB.Pb.2008/339 with three fragmentary leaflets see enlargement in Fig. 9B ), Ulina . D. Probable trifoliolate leaf MGUWr 5618p with two incompletely preserved leaflets, Ulina . E. Incomplete trifoliolate leaf MB.Pb.2008/346, Ulina .

gene pedate, palmate, and trifoliolate compound leaves were observed by several authors (see historical account in Krassilov et al. 2005: 124–125), but taxonomic treatments and palaeobiological interpretations diverged widely. Rather than using a widely understood and manifestly artificial grouping, we follow Krassilov et al. (2005) in recognising an informal Debeya group encompassing a few fossil-genera with several species, but excluding species of globally similar morphology, yet distinguished by minute morpho- logical details believed to be of taxonomic significance.

A palaeobiological interpretation of Cretaceous leaves without attached reproductive structures is largely hypothetical, but two suppositions on the systematic placement of the Debeya group that have been argued for in most detail (Platanales: Crane 1989; Ranunculales : Krassilov et al. 2005: 126) are as a matter of fact easily reconcilable, insofar as the two above-mentioned orders are phylogenetically very close to each other. It might thus be supposed that the Debeya group belongs to extinct representatives of basal eudicots (herein subclass Ranunculidae). It would, however, be premature, to formally propose such a systematic treatment. The species to be excluded from the Debeya group as understood herein are those interpreted as members of the Chloranthaceae (Cenomanian of Bohemia; JK, unpublished data; see also Halamski 2013: 419) or of the Fagales (see above).

The oldest undisputed representatives of the Debeya group are from the Turonian of Negev ( Israel; Krassilov et al. 2005) and the youngest uncontested ones are from the Paleocene. However, similar plants in need of revision were reported from strata as old as Cenomanian and as young as Oligocene ( Crane 1989 and references therein).

Figures

Fig. 9. Fagalean angiosperm Dryophyllum westerhausianum (Richter, 1904) Halamski and Kvaček comb. nov. from Ulina, North Sudetic Basin, Lower Silesia, Poland, Assemblage 6 (lower–middle Santonian). A. Fragmentary leaflet MGUWr 5619p showing venation and serration. B. Enlargements of venation of fragments of two leaflets MB.Pb.2008/339 (see the entire specimen in Fig. 8C). C. Probable trifoliolate leaf MB.Pb.2008/0342 with two fragmentarily preserved leaflets.