Révision de la Collection Jesse Harlan JOHNSON. Première partie. Quelques Dasycla-dales fossiles du Guatémala

Ce premier rapporte traite de la révision de quelques algues calcaires vertes fossiles (Dasycladales), ou supposées telles (dans les faits un de ces taxons attribué au genre Cylindroporella est un foraminifère), décrites de terrains crétacés et paléocènes du Guatémala. Dans leur papier de 1965 J.H. JOHNSON and H.V. KASKA avaient entre autres choses introduit trois nouvelles espèces attribuée à l'origine aux genres Acroporella, Cylindroporella et Cymopolia.This first report is a revision of fossil calcareous green algae (Dasycladales) described from the Upper Cretaceous and Paleocene series of Guatemala. Among other things in their 1965 paper J.H. JOHNSON and H.V. KASKA introduced three new species originally referred to the genera Acroporella, Cylindroporella, and Cymopolia. One species, which has previously been referred to the genus Cylin-droporella, is a foraminifer

Paleocene orthophragminids from the Lakadong Limestone, Mawmluh Quarry section, Meghalaya (Shillong, NE India). Implications for the regional geology and paleobiogeography

The late Paleocene orthophragminids, hitherto poorly known from the Himalayan foreland basins, are studied from the Lakadong Limestone in Meghalaya, northeastern India, in order to establish a systematic, biostratigraphic, and paleobiogeographical framework for them in the eastern Tethys. In the Mawmluh Quarry section (MQS) on the Shillong Plateau, to the southeast of Tibet, orthophragminids are associated with typical Paleocene orbitoidiform taxa endemic to the Indian subcontinent, i.e., Lakadongia Matsumaru & Jauhri ( D Setia Ferràndez-Cañadell) and Orbitosiphon Rao, and various species of alveolinids, miscellaneids, and rotaliids, characterizing the Shallow Benthic Zones (SBZ) 3 and 4. The orthophragminids belong to two lineages of the genus Orbitoclypeus Silvestri: O. schopeni (Checchia-Rispoli) and O. multiplicatus (Gümbel), both well known from the peri-Mediterranean region and Europe (western Tethys). The latter species is identified here for the first time from the eastern Tethys. Previous records of the genus Discocyclina Gümbel from the Lakadong Limestone actually correspond to misidentified Orbitoclypeus; this implies that the late Paleocene orthophragminid assemblages from Meghalaya and eastern Tethys were less diverse than in the western Tethys. The lineage of Orbitoclypeus schopeni in the lower part of the Lakadong Limestone (SBZ 3) is identified as O. schopeni cf. ramaraoi based on the morphometry of a few specimens, whereas in the upper part (SBZ 4) it corresponds to a transitional development stage between O. schopeni ramaraoi and O. schopeni neumannae (with average Dmeanvalues ranging between 192 and 199 μ m). The embryon diameters of O. multiplicatus, recorded only in SBZ 4, range between 300 and 319 μ m on average, corresponding to transitional development stages of O. multiplicatus haymanaensis and O. multiplicatus multiplicatus. Our data, along with a review of previous Paleocene and Eocene records from India and Pakistan, suggest that Orbitoclypeus is the only orthophragminid in the Paleocene of the eastern Tethys, whereas Discocyclina first appears in early Eocene times, being mainly represented by endemic taxa confined to the Indian subcontinent. Facies change in the MQS from a marine to continental setting within SBZ 4 corresponds to the oldest record from the Indian plate in the Paleogene, which may be linked to the flexural uplift of the passive margin of the Indian plate, marking the onset of the collision of the Indian and Eurasian plates

Decastronema barattoloi (DE CASTRO), characteristic fossil of the Palaeocene and the Eocene peritidal sediments from the Adriatic carbonate platform

The renewed deposition in the Palaeogene and the oldest part of the non-interrupted Palaeocene succession is characterized by the presence of Decastronema barattoloi (DE CASTRO), cyanobacterial tubes originally described in the Apennines. The reinterpretation of limestones from several sections located in the Kras region (NW part of the AdCP: Basovizza, Dolenja vas, Sopada, Čebulovica) confirmed the presence of these microfossils in peritidal sediments of Danian age (SBZ 1). The Cuisian (Late Lower Eocene) sediments, from eastern Istria (Brnjci section), Cres Island (Koromačna Cove section) and Ravni kotari (Benkovac–Korlat section) contain individuals of this species in great numbers. The cyanobacterial tubes are scattered in laminated, fine grained mudstones and wackestones, immediately above the Cretaceous sediments (occasionally above bauxites or breccias). The Decastronema-bearing sediments pass upward into the Foraminiferal limestones of Cuisian age (SBZ 11, based on conical agglutinated foraminifera and alveolinids), allowing the age determination of the cyanobacterial remnants. The Palaeocene specimens are minute (up to about 180 μm long), thick walled tubes that occur with the index fossil Bangiana hanseni DROBNE. The Eocene forms accompanied by ostracods, pelecypods, and miliolid and rotaliid foraminifera are segmented tubes, up to 400 mm long and usually thin walled

Larger miliolids of the Late Cretaceous and Paleogene seen through space and time

Spatial and temporal occurrences of the larger (complex) miliolids are discussed to give more light on biostratigraphy and paleobiogeographic provinces distribution. Seven generaand 47 species from the Late Cretaceous to Oligocene inhabited shallow marine settings in the Indo-Pacific, Tethyan and Caribbean regions. Of all genera only four (Idalina, Periloculina, Pseudolacazina, Lacazina) widespread throughout Tethys in theLate Cretaceous and Paleogene. Single occurrence of Lacazina was recorded further to east (Moluccas). By now the Late Cretaceous genus Adrahentina is known only from the Spain. The newcomer’s Eocene genera were Fabularia and Lacazinella. Fabularia reachedhigh diversity in species term in the Central and Western Tethys and occured as unique genus in Caribbean realm, too. Conversely, during the same period, Lacazinella spread over the southern border of Neo-Tethys reaching New Guinea.On the Adriatic – Dinaric Carbonate Platform, larger miliolids occurred from the Late Cretaceous to Cuisian, having the same biostratigraphically trends and distribution as contemporaneous larger miliolids from the Tethys