in Jurassic and Cretaceous Stratigraphy

Earth Science Frontiers, Vol. 17, Special Issue, Aug. 2010 ISSN 1005-2321
Conifer Diversity in Sehora, Jabalpur Formation, Satpura Basin, India
Neeru Prakash
Birbal Sahni Institute of Palaeobotany, 53-University Road, 226007, Lucknow, India (E-mail: neerup_in@yahoo.com)
Sedimentary deposits of Jabalpur Formation are
exposed along the Narbada River in Satpura Basin.
These outliers mainly occur between Mahadevas and
Lametas at Mahadeva Hill and extend laterally to
Bairam and Belkher areas in the western part of central
India. These sedimentary deposits represents highest
Gondwana strata, embody significant floral assemblage.
The highly diversified plant fossils are preserved in the
vicinity of Sher River near Sehora, in compressed state,
usually found in blackish-grey carbonaceous shale. The
high diversity of conifer macrofossils are represented
by number of species of Brachyphyllum, Pagiophyllum,
Araucarites, Elatocladus and Coniferocaulon, dis-
playing wide range of foliar morphology and cuticular
variations.
Podocarpaceae is the predominant family of coni-
fers in the Southern Hemisphere, is well represented by
sterile and fertile twigs of genus Elatocladus, exhibit
Conifers first appeared in early to late Triassic,
thrived well during Jurassic and steadily diversified till
Early Cretaceous period. The flora of Jabalpur (Sehora)
is one of the richest floras among Indian Gondwana
representing 49% conifers, 22% pteridophytes, 17%
bennettitales, 1% ginkgo and pteridosperms (Prakash,
2008). Among these conifers are floristically dominant
and considered as a significant components of Gond-
wanan vegetation comprising plants of families Podo-
carpaceae, Araucariaceae along with incertae sedis
elements. The assemblage is coeval to Rajmahal type-2
helically arranged leaves that ranges from scale to
linear or broad leaves. Thickness of cuticles show
variations in upper (thin) and lower cuticles as they are
comparatively thick. Stomata are sunken and arranged
in stomatal bands. Araucariaceae is mainly represented
by detached leafy twigs of genus Brachyphyllum,
Pagiophyllum and cone scales of Araucarites. Here
leaves are closely ad-pressed, conical or hexagonal to
short falcate or lanceolate types and cone scales are
typically wedge shaped, minute to large sized. The
cuticles of genus Pagiophyllum and Brachyphyllum
exhibit both upper (thin) and lower thick cuticles with
sunken stomata arranged within the stomatal bands.
Sometimes stomatal hairs are also observed in stomatal
pit suggesting its thermophyllous nature. Both the
families are cosmopolitan in southern hemisphere, but
they grew and evolved simultaneously in northern
hemisphere (Krassilov, 1974).
Fig.1 Map showing locality Sehora in Satpura Basin
flora of Nipania which also embody Araucarian and
Podocarpacian fossil remains, but differ in presence of
Pentoxyleae group. The plant fossils of East-Coast
occur in isolated patches of Early Cretaceous deposits
characterized by broad-leaved cycadophytic leaves;
however, floral assemblage of Gollapalle is com-
paratively closer to present floral assemblage, where
conifers are dominant over the cycadophytes and
pteridophytes (Pandya and Sukh-Dev, 1990) with
common occurrence of Elatocladus, Pagiophyllum,
Brachyphyllum and Araucarites. The flora of Bluff
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