Palm Pollen and the Fossil Record


Harley, Madeline Margaret 1996. Palm Pollen and the Fossil Record. Thesis University of East London
AuthorsHarley, Madeline Margaret

Previously published descriptions of the pollen morphology of the Palmae are
reviewed and discussed. The earliest macro fossil records for palms are
summarised, while a more detailed review is given of the fossil records of palmlike
pollen. Selected literature relating to pollen sharing some similarities to palm
pollen in other monocotyledonous families are briefly reviewed, and the fossil
pollen records for these families are examined. A brief chronological account of
earlier systematic treatments of the palms is provided, as well as an outline of the
systematic treatment of the family used in the present account.
The pollen morphology of 1150 collections, representing 765 species of
palms,f rom all but seveno f the currentlyr ecognisedg enera,h asb eene xamýined,
as well as dispersedp alm-likef ossil pollen from the middle Eoceneo f the Isle of
Wight, and of Java. Iii silit pollen of fossil palm flowers from the Messel oil shales
(Germany)a re describedP. ost meiotic tetrad stageh asb eens tudiedf or
representatives peciesin all subfamiliese xceptingt he PhytelephantoideaeP.o llen
morphologyo f both recenta nd fossil pollen is describedf rom light, scanning
electrona nd, selectivelyf rom transmissione lectronm icroscopy,w hile tetrad
resultsa re from light and scanninge lectronm icroscopy.F ull detailso f preparation
methods,t erminologya nd databaseus sedf or pollen morphological,f ossil and
tetrad studies are given.
Seventeena perturet ypes,p lus numerouss ubtypesa, nd twelve exine types
with numerous subtypes are identified. The aperture types are shown to be
broadly separablein to two groupsw hich are associatedw ith either simultaneous
(tetrahedralt etrads)o r successive(t etragonalt etrads)m icros porogenessi. In
generalt heset wo groups supportp resents ystematico pinion regardingt he
subfamilies.S uccessivem eiosisi s dominanti n subfamiliesC alamoideaea nd
Nypoideaew hile, with somer are exceptionss, imultaneousm eiosisp redominates
in the remainingf our subfamiliesC: oryphoideaeC, eroxyloideaeA, recoideaea nd
PhytelephantoideaeP.o llenu ltrastructurei s treatedi n detail only for simple
tectate exines where it is important for further definition. Six types and a number
of subtypesa re described.T he systematicd istributionso f aperturea nd exine
types are summarisedA. trend towardsl arger pollen is noted, with the smallest pollen occurring in the least specialised subfamily, the Coryphoideae, while very
large-sized pollen are characteristic of subfamily Phytelephantoideae.
Monosulcate, disulcate and zonosulcate pollen are described from fossil material
and closest affinities with recent palms suggested.
Pollen morphology of recent palms is summarised and discussed, and
compared with pollen of selected monocotyledonous families. The bearing of
pollen data on recent palm systematics is considered at various levels from
subfamily to species. Angiosperm pollen evolution is re-considered and
evolutionary pathways for palm pollen aperture types and exine types are
suggested. In the light of recent pollen morphology for the family the fossil record
of palm pollen is re-evaluated. Some widely accepted affinities are challenged
while previously unconsidered affinities are suggested, particularly for the mid-
Cretaceous. The need is emphasized for future fossil pollen studies to look
critically for pre Late Cretaceous palm-like monosulcates, which would be more
informative of the early history of the family than the apparently highly evolved,
easily recognisable Spini. -onocolpiles of the Late Cretaceous. Palaeogeography,
environment and distribution of fossil records and depositional environment are
Probable evolutionary pathways of pollen morphology, including pollen
tetrad data which suggests imultaneousra thert han successivem eiosisa s the
plesiomorphics tate,o ffer further evidencet hat the palmsa re indeeda n ancient
group, and support the hypothesis that the palms may have originated in South
America and Africa (West Gondwana)in the Late Jurassic or early Cretaceous,
prior to the complete separation of these continents.

Keywordspalm pollen; pollen morphology; macro fossil records
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Publication dates
PrintNov 1996
Publication process dates
Deposited11 May 2011
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