Xylotomical Comparision of Fossil Wood with Living Wood of the Sapotaceae Family, from Manchar Formation Exposed at Thano

A new silicated wood fossil related to the Sapotaceae family was identified from Quaternary Manchar beds of Thano Bula Khan (Paleoforest), Jamshoro, Pakistan. The xylotomic characteristics of the present fossil wood, i.e., diffuse porous wood, parenchyma tissue structure, rays and pits indicated close attributes with the genus Sapota belonging to family Sapotaceaee. The taphonomic evidence of the fossilized remains inferred that the tree from possessing fossilized wood was developed in situ , but was carried into the current location from another region


Introduction
Since the early Blanford study (1879), the existence of the fossil dicot and monocot forests in the upper Tertiary and Quaternary deposits of Pakistan has been identified.Many authors have described and documented species of petrified wood from various locations in Sindh.The most recent are from Bara Formation of Ranikot was identified by Mangi et al. (2020) and from Manchar formation of Thano Bula khan by Soomro et al . 2021 Further, Manchar formation Some of the existing publications on fossil plants provides special aid for the identification of remains of fossil wood included Soomro et al., (2017); Khan et al. (2016); Ahmed et al., (1991aAhmed et al., ( ,b,c, 1993;;2001, 2007a,b) and Shar et al. (2007).In addition, three new species were also identified from Punjab, Pakistan (Soomro et al., 2014, Soomro et al., 2016 a & b).Present research focuses on the anatomical description and fossil wood comperission with living wood and already reported wood collected from Manchar Formation near the Thano Bula khan, Jamshoro district, Sindh (Fig. 1).

Material Method
Three-dimensional sections of the fossil wood were prepared as described by Weatherhead (1938).Most of the studies were done with a simple light microscope and images were photographed through German Ortholux Microscope.

Fossil Description Morphological Description
The preserved wood was consisted of one piece of wood deposition of silicates, measuring about 0.13 cm.long and 7 cm broad.The colour is light brown and shiny Anatomical Description Genus -Sapotoxylon Felix, 1882 Sapotoxylon thanobulansis sp.nov.
Topography:-Wood diffuse porous.Growth rings not clearly seen.Vessels small to medium -sized, mostly medium, solitary and mostly in radial multiples of 2-5, (Plate 1; Figs.2-6) occasionally up to 8, exhibiting short chain-like structure, characteristically grouped together in oblique radial line forming zig zag flame-like pattern, about 30-60 vessels per sq mm; tyloses present, thick-walled, vessels also filled with whitish crystalliferous contents.Vasicentric tracheids occurring in the immediate vicinity of vessels and vessel groups.Parenchyma paratracheal and apotracheal, the former vasicentric, only a few row of cells associated with the vessels, intermingled with vasicentric tracheids, while the latter forming more or less loose, wavy as well as straight, regular lines, 1-5 (mostly 2-4) seriate in width, about 4-9 lines per mm.Xylem rays fine, 1-4 seriate, mostly 3, and occasionaly 4, 7-22 cells in height and 8-19 rays per mm; ray tissue heterogeneous, rays heterocellular, consisting of procumbent cells through the median portion and one-seral uniseriate marginal rows of upright cells at both the ends.Fibres aligned in radial rows between two consecutive rays (Plate 2; Figs.

Comparison with living counterparts
The above features of the fossil clearly show that it is a sapotaceous wood.The family Sapotaceae, on the whole, is quite homogenous in wood structure.There is hardly any characteristic feature in the woods having diagnostic value in the generic distinction.However, they can be distinguished only in certain cases when all the characters of the woods are taken into consideration collectively.After examining the available thin sections of modern woods as well as published description and illustrations of quite a number of woods of the described family (Desch, 1954;Kribs, 1959;Lecomte and Guibier, 1926;Metcalf & Chalk, 1950;Normand, 1960 andPearson &Brown, 1932), it was found that the fossil shows general resemblance with some species of Mimusops, Manilkara, Payena, Bequaerrtiodendron (Neoboivinella) and Pachystela.
Manilkara and Mimusops exhibited some significant variations with regards to the size and arrangement of the vessels, the type of parenchyma and rays.The size of vessels varies from small to large, arranged in loose to compact groups arranged in loose to compact groups along oblique radial lines; the parenchyma lines are 1-3 serate, close or slightly widely spaced; the rays are 1-2 or up to 4-seriate.In the present fossil the vessels are mostly medium, with majority of vessels being more than 100 μm in diameter, arranged in groups as well as along oblique radial lines; the parenchyma lines are 1-5 seriate and closely spaced, and the rays are only 1-4 seriate.It is evident that the possibility of being either Manilkara or Mimusops as its modern equivalent can not be ruled out.In the nature and distribution of vessels and parenchyma and in the width of rays, it is also somewhat similar to those of Payena.However, the vessels in Payena are slightly bigger than those of the fossil.In the type and distribution of vessels and parenchyma, the fossil also shows resemblance with

Bequaerrtiodendron glomeruliflora
Aubr. and Pachystela brevipes Baill.(Normand, 1960).However, the former differs from the fossil in having slightly smaller vessels (i.e. the diameter being less than 100 μm), while the latter differs in having rays up to 4-seiate.Since the fossil exhibits all the anatomical characters of the family Sapotaceae, it is assigned to the genus Sapotoxylon Felix (1882).

Comparison with already reported fossil wood species
So far with species of fossil woods of the family Sapotaceae are known.These are Sapotoxylon taeniatum (Felix, 1882) from Bavaria in south-east Germany.Manilkaroxylon diluviale (Hofmann, 1944) from the Quaternary deposits of South America, Manilkaroxylon crystallophora and Palaeosideroxylon flammula (Grambast-Fessard, 1968) from the Upper Miocene of Castel-lane in south-east France, Siderinium deomatliense Prakash & Awasthi (1970) from the Mio-Pliocene of Deomali, Arunachal Pradesh.Manilkaroxylon bohemicum and Sapotoxylon pacltovae (Prakash et al., 1974) from the Tertiary of South Bohemia, Czechoslovakia, Chrysophyllxylon indicum Awasthi (1977) from the Mio-Pliocene beds, near Pondicherry, India and Madhucoxylon cacharense Prakash & Tripathi (1976) from the Tipam Seiresm, near Hailandandi, Assam.All these species are quite different from the present fossil wood.
In Sapotoxylon taeniatum the vessels are slightly bigger (diameter 180 μm), rays 2-3 seriate and parenchyma line 3-celled or even broader.The vessels in Palaeosideroxylon flammula are very much crowded and grouped forming dendritic patterns and the parenchyma lines are 2-3 seriate and widely space.In Aamnikara crystallophora the rays are 1-4 seriate with swollen and crystalliferous upright cells, and the vessels are arranged in distinct radial lines without forming zigzag or flame-like pattern.Similarly, in Siderinium deomatliense and Madhucoxylon cacharense, the vessels are in derail line without forming zig-zag pattern and the parenchyma is diffuse or in uniseriate lines.In Manil-karoxylon bohemicum the vessels are mostly large (t.d.50-290 μm, r.d.50-310 μm) and the rays are 1-3 seriate.The frequency of the vessels in Sapotoxylon pacltovae is very less (2-4 vessels per sq mm) and their size ranges between 75 to 200 μm in diameter, and the apotracheal parenchyma lines are uniseriate only.In Chyropyloxylon indicum the vessels are large and the xylem rays are 1-4 seriate, whereas in the present Ethipian fossil wood the vessels are mostly smaller (t.d. 48-100 μm, r.d. 32-120 μm), arranged in long radial multiples forming zig-zag patterns, the xylem rays are 1-2 seriate and the parenchyma is scanty paratracheal and in regular lines from 1-3 mostly 1-2 cells in width.Detailed comparision of reported fossil wood with fossil under invetigation with in same genus of sapota given in (Table 1).
It is seen that the present fossil is quite different from all the above species.It is, therefore, described as a new species of Sapotoxylon felix, Sapotoxylon thanobulansis sp.nov.

Conclusions
Anatomical analyses of the fossil wood with the present wood have shown that the fossil wood is more comparable with the living wood of the Sapota genus and hence has given the name Sapotoxylon thanobulansis Sp Nov. further, the occurance of diffuse porous fossil wood and other anatomical features indicated the prevalence of tropical climate during the deposition phase of sedimentation.Fossil samples indicated that the tree from which the fossil wood had been developed was not growing in situ but transported from some other areas, into the present location.https://isciencepress.com/index.php/Jqaas

Table 1
et al., https://isciencepress.com/index.php/Jqaas97 Comparison of fossil woods related to the genus Sapatoxylon, age and Geological distribution