Volume 17, Issue 3
March 1943, pages 59-96
pp 59-96 March 1943
Enigmocarpon Parijai is one of the commonest of the silicified fruits in the chert beds at the base of the Intertrappean Series at Mohgaon Kalan in the Deccan. The structure shows a combination of characters found in no other known genus and only in the family Lythraceæ; its nearest known allies are the generaDecodon andHeimia.
Both fruit and seed were adapted for aquatic dispersal and seem to have been fitted for long immersion in brackish water. Among associated fossils are the remains of many other aquatic or marsh plants, including a species ofNipa, an estuarine genus known for its wide distribution along the coast of the old Tethys Sea, nearly always in strata of Eocene age.
The occurrence ofEnigmocarpon in this flora lends further support to a Tertiary age for the Deccan beds, because no trace of Lythraceæ has yet been found in any older rocks.
The author gives a sketch of the geological history of the Lythraceæ. Fossil representatives of the family are now known from the Eocene of the Thames basin and of the Deccan; from rocks of Oligocene to Miocene age in several parts of Germany; from the Mio-Pliocene of France; from the Pliocene of Holland, Belgium and Central Russia; lastly, from the Pleistocene (Karewa beds) of Kashmir.
There is good evidence that the amphibious habit still seen in many Lythracæ was an ancient characteristic of the family, much more wide-spread in early Tertiary times than it is to-day. The spongy tissue in the seeds of some modern genera,e.g., Lagerstroemia andLawsonia, which are not known for any special preference for damp habits, is probably a relic of an amphibious ancestry.