Alanlordella bentonensis Morrow 1934 from: Boudagher-Fadel, M.K.Banner, F.T.Whittaker, J.E.Simmons, M.D. (1997): Early Evolutionary History of Planktonic Foraminifera. Vol. 1 . |
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Species Alanlordella bentonensis Morrow 1934 |
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Diagnosis / Definition: |
Boudagher-Fadel et al. (1997):
Diagnosis: Test planispiral, about 210-360 µm
at its maximum diameter, biumbilicate; six to
seven chambers in the last whorl, globular, almost
as high as broad, increasing rapidly in size; sutures
radial and depressed; aperture interiomarginal,
equatorial, symmetrical, extending laterally into
each umbilicus for half of the last whorl, furnished
with portici; wall smooth, not muricate, but
macroperforate in the early part of the last whorl;
the macroperforations are visible only in the early
part of the whorl, but the later chambers retain the
microperforations of this species' ancestors. |
Discussion / Comments: |
Boudagher-Fadel et al. (1997):
Remarks: In rare specimens, later in the Early
Albian, the antepenultimate chamber develops a
tubulospine (Plate 12.1, Fig 9) like Schackoina.
Anomalina eaglefordensis Moreman (1927),
considered by Loeblich and Tappan (1961) to be
a senior synonym of this species, was subsequently
confirmed as a benthonic species (Low,
1964; Pessagno, 1967) and all the planktonic
individuals referred to it were placed by them in
Globigerinelloides caseyi (Bolli, Loeblich and
Tappan), a species first described from the Albian
Gault Clay of England. However, after examination
of topotype material, Carter and Hart (1977,
p. 28) rejected the name caseyi using G. bentonensis
for the Late Albian and Cenomanian forms
found in the British succession.
A suite of specimens from Tunisia and from
the Gault Clay Formation, Arlesey brick pit,
Cambridgeshire (the type locality of G. caseyi) are
illustrated in Plate 12.3, Figs 1-9, Plate 12.4, Figs
1-9) and these have been matched with Bolli,
Loeblich and Tappan's original illustrations of
caseyi, and with those of 'G' bentonensis
(Morrow). All are considered conspecific. Moreover,
the Tunisian and the English specimens are
identical in that the last formed chambers are still
microperforate (like the ancestral Blowiella) but
the early chambers of the last whorl have become
macroperforate. This species is transitional from
microperforate Blowiella to the macroperforate
Alanlordella. In the latter genus muricae begin on
the early chambers of the last whorl and are absent
on the later chambers. This evolution is clearly
protogenetic in that the morphological features of
the adult ancestors are recapitulated in the latest
stages of life while the newly evolved characters
(macroperforations and muricae) appear in the
early stages of ontogeny during evolution. They
later extend to all growth stages, and with the
acquisition of muricae become true Alanlordella.
On the other hand, the umbilicus of A. bentonensis
is wider than in typical Blowiella but it has
not reached the great width of typical Globigerinelloides.
Carter and Hart (1977) and Hart et al. (1981)
were correct in considering that A. bentonensis
arose from Blowiella, but the species of immediate
ancestry has yet to be determined. |
Systematics: |
22 Superfamilia Globigerinaceae
Familia Planomalinidae
Genus Alanlordella
Species Alanlordella bentonensis
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Synonym list: |
Boudagher-Fadel et al. (1997):
1997 Alanlordella bentonensis Morrow. - Boudagher-Fadel et al. : p. 221, 223 pl. 12.3, fig. 1-9;
pl. 12.4, fig. 1-9;
Figure: 12.1
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Was used in synonym list of: |
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References: |
Morrow,A.L. (1934): Foraminifera and Ostracoda from the Upper Cretaceous of Kansas . Journal of Paleontology Vol. 8 p. 186–205
Bolli,H.M.; Loeblich,A.R. and Tappan,H. (1957): The Planktonic foraminiferal families Hantkeninidae, Orbulinidae, Globorotaliidae, and Globotruncanidae . U.S. National Museum Bull. Vol. 215 p. 3-50
Low,D. (1964): Redescription of Anomalina eaglefordensis Moreman . Contributions from the Cushman Foundation for Foraminiferal Research Vol. 15 p. 122, 123
Salaj,J. and Samuel,O.. (1966): Foraminiferen der Westkalpaten-Kreide (Slowakei) . Geologický Ústav Dionýza Stúra, Bratislava p. 292
Pessagno,E.A. (1967): Upper Cretaceous planktonic foraminifera from the West Coastal Plain . Palaeontographia Americana Vol. 5 p. 259-441
Wonders,A.A.H. (1975): Cretaceous planktonic foraminifera of the Planomalina buxtorfi group from El Burrueco, southern Spain . Koninklijke Nederlandse Akademie van Wetenschappen, Amsterdam, Proceedings, Series B Vol. 78 p. 83-93
Masters,B.A. (1977): Mesozoic Planktonic Foraminifera. In: Oceanic Micropalaeontology Eds: Ramsay, A.T.S. p. 301-731
Carter,D.J.. and Hart,M.B.. (1977): Aspects of mid-Cretaceous stratigraphical micropalaeontology . Bulletin of the British Museum (Natural History) (Geology) Vol. 29 p. 1-135
Salaj,J. (1980): Microbiostratigrayhie du Crétacé et du Paléogéne de la Tunisie septentrionale et orientale (hypostratotypes tunisiens) . Geologický Ústav Dionýza Stúra, Bratislava p. 238
Hart,M.B..; Bailey,H.W..; Fletcher,B..; Price,R.. and Sweicicki,A.. (1981): Cretaceous. In: Stratigraphical Atlas of Fossil Foraminifera Eds: Jenkins, D.G.Murray, J.W. p. 149-227
Ben Haj Ali,N.. (1987): Étude biostratigraphique du Crétacé (Aptien á Cénomanien) de la Région du Teboursouk (Tunisie septentrionale) sur la base des foraminiféres planctoniques . Notes du Service Géologique Tunisie Vol. 54 p. 75-105
Boudagher-Fadel,M.K. (1995): The planktonic foraminifera of the Early Cretaceous of Tunisia compared to those of western and central Tethys . Paleopelagos Vol. 5 p. 137-160
Boudagher-Fadel,M.K.; Banner,F.T.; Whittaker,J.E. and Simmons,M.D. (1997): Early Evolutionary History of Planktonic Foraminifera. Vol. 1
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