Wl. Crepet et Kc. Nixon, 2 NEW FOSSIL FLOWERS OF MAGNOLIID AFFINITY FROM THE LATE CRETACEOUS OF NEW-JERSEY, American journal of botany, 85(9), 1998, pp. 1273-1288
Two taxa of cupulate magnoliid fossil flowers, Cronquistiflora and Det
rusandra, are described from the Late Cretaceous (Turonian, similar to
90 million years before present [MYBP]) Raritan (or lower Magothy) Fo
rmation of New Jersey. The fossil taxa are represented by flowers at v
arious stages of development, associated fragments of cup-shaped flora
l receptacles with attached anthers, and isolated anthers. Both taxa h
ave laminar stamens with adaxial thecae and valvate dehiscence. Pollen
is boat-shaped and foveolate in anthers associated with Cronquistiflo
ra and spherical with reticulate ornamentation in Detrusandra. Cup-sha
ped receptacles are externally bracteose in both taxa. The receptacle
of Cronquistiflora is broader than the campanulate one of Detrusandra.
Cronquistiflora also has more carpels (similar to 50 in a spiral vs.
similar to 5 in a whorl or tight spiral). In Detrusandra the carpels a
re surrounded by dorsiventrally flattened structures (pistillodes?) th
at are remote from the attachment of the stamens near the distal rim o
f the receptacular cupule. Detrusandra stigmas are rounded and bilobed
, while those of Cronquistiflora, although bilateral in symmetry, are
somewhat peltate. The fossil taxa share prominent characters with exta
nt cupulate magnoliids (e.g., Eupomatia, Calycanthus), but also share
characters with other magnoliids including Winteraceae. These fossils
represent taxa that are character mosaics relative to currently recogn
ized families. Inclusion of these fossils in existing data matrices an
d ensuing phylogenetic analyses effect changes in tree topologies cons
istent with their mosaicism relative to modern taxa. But such analyses
do not definitively demonstrate the affinities of the fossils other t
han illustrating that these fossils are generalized magnoliids. Additi
onal analysis of modern and fossil magnoliids is necessary to fully ap
preciate the phylogenetic significance and positions of these fossil t
axa. However, the results of the phylogenetic analyses do introduce th
e possibility that extinct taxa of Magnoliales with cupulate floral re
ceptacles were transitional between basal angiosperms and those with t
ricolpate pollen. The fossils provide insights into the timing of evol
ution of character complexes now associated with coleopteran pollinati
on.