. Bulletin of the British Museum (Natural History) Geology Supplement. 9-2 CALCAREOUS ALGAE OF THE MIDDLE EAST but Broeckella, Clypeina and Terquemella occur in both as well as in the Middle East, and Pagodaporella is so far known only from the Middle East. This assortment of genera in the very sector of the Tethys which in mid-Tertiary was to become the land barrier dividing the marine Mediterranean-Antilles from the Indo-Pacific is no doubt significant for the modern discontinuous distribution of dasyclads, even if most of the genera quoted are now extinct. The distribution-maps (Figs. 8-14)
. Bulletin of the British Museum (Natural History) Geology Supplement. 9-2 CALCAREOUS ALGAE OF THE MIDDLE EAST but Broeckella, Clypeina and Terquemella occur in both as well as in the Middle East, and Pagodaporella is so far known only from the Middle East. This assortment of genera in the very sector of the Tethys which in mid-Tertiary was to become the land barrier dividing the marine Mediterranean-Antilles from the Indo-Pacific is no doubt significant for the modern discontinuous distribution of dasyclads, even if most of the genera quoted are now extinct. The distribution-maps (Figs. 8-14) illustrate different aspects of past and present dasyclad occurrences. The value of these dated fossil occurrences may be seen by a comparison with the distribution-maps of Svedelius (1924) which, whilst taking account of former continuous sea-ways, show only Recent distribution. The work of Kaever (1965), on the micropalaeontology of Afghanistan, contains numerous records of Tethyan algal species familiar in the Middle East. Unfor- tunately this paper came too late to my notice for inclusion of the detailed species records. VI. ECOLOGY At the present day dasyclads are a relatively inconspicuous element in marine algal floras. Although life has sometimes taken me to warm-water shores, I have never seen or collected living dasyclads. Their ecology has been briefly summarized by Pia (1920), Cloud (1962) and Johnson (1961b), all palaeontologists, for comparison with fossil occurrences. They occur in warm shallow coastal waters in sheltered situations in tropical and subtropical seas, and in areas marginal to the latter, such as the Mediterranean. Their maximum abundance is said to be from low-tide level to 5-6 m. depth, extending down in diminishing abundance to 10 m., and with scattered occurrences below this to 30 m. or more, depending on intensity of illumination and. Distribution of the Polaeocene Pagodaporella, and its possible living descendant Dosyclodus. Approximate Telhy
Size: 2225px × 1123px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorbritishmuseumnaturalhistory, bookcentury1900, bookcoll
