15^ UPPER CRETACEOUS-LOWER TERTIARY FORAMINIFERA 



Globorotalia and Globigerina species from Maestrichtian strata, probably belong to the 

 present species. 



Hypotype. P.45664. 



Horizon and locality. Hypotype from sample No. 21, Wadi El-Sharawna 

 section. 



Hedbergella petaloidea (Gandolfi) 



1955 Globotruncana (Rugoglobigerina) petaloidea petaloidea Gandolfi : 52, pi. 3, figs. \},a-c. 



1955 Globotruncana (Rugoglobigerina) petaloidea subpetaloidea Gandolfi : 52-53, pi. 3, figs. 



I2U-C. 



1956 Globigerina compressa Plummer ; Hofker : 76, pi. 9, figs. 6ja-c. 

 i960 Rugoglobigerina jerseyensis Olsson : 49, pi. 10, figs. 19-21. 



1962 Praeglobotruncana (Hedbergella) petaloidea (Gandolfi) ; Berggren : 41-43, pi. 7, figs. ^a-c. 



Remarks. Hedbergella petaloidea ranges throughout the Maestrichtian part of the 

 sections studied as a rare to common form. It is believed to have evolved into 

 Globotruncana havanensis Voorwijk by the lateral compression of the chambers in the 

 last whorl, by the development of a roughly concavo-convex test, by the confinement 

 of the aperture to an interiomarginal-umbilical position, and by the development of 

 the umbilical tegilla, the keel or keels and the imperforate peripheral band. This 

 is suggested by the recorded tendency of H. petaloidea to shift the aperture to a some- 

 what umbilical position and to develop a pinched out pseudo-keel and slightly 

 compressed chambers, and is substantiated by the several transitional stages which 

 were described by Gandolfi as G. (R.) petaloidea subpetaloidea. However, both 

 Gandolfi (1955) and Berggren (1962) considered H. petaloidea to have evolved from 

 G. havanensis, despite the fact that the general tendency in the evolution of these 

 forms is towards the development of carinate tests and more flattened chambers. 



The species was originally described by Gandolfi (1955) from the Maestrichtian 

 Colon shale of northeastern Colombia as Globotruncana (Rugoglobigerina) petaloidea 

 petaloidea. However, its extraumbilical-umbilical aperture and weakly developed 

 umbilical portici distinguish it from both Globotruncana and Rugoglobigerina, and 

 justify its assignment to Hedbergella. Again, the form described by Gandolfi (1955) 

 as G. (R.) petaloidea subpetaloidea differs from the present species in having only a 

 weakly developed pseudocarina. However, as the tendency to have a pinched out 

 periphery in the form of a pseudocarina was clearly observed in the central form, the 

 latter subspecies falls well within its range of variation and is thus considered 

 synonymous. 



Olsson (i960) described as R. jerseyensis from the Maestrichtian Redbank forma- 

 tion of New Jersey, a form which is identical with the present species, while Hofker 

 (1956c) confused it with G. compressa (Plummer) when he described the latter species 

 from the Maestrichtian of northwestern Germany. 



Hypotype. P.45665. 



Horizon and locality. Hypotype from sample No. 27, Wadi El-Sharawna 

 section. 



