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First report of Acanthochaetetes (Porifera: Demospongiae) from the Cretaceous Khalsi Formation, Ladakh Himalaya, India

Published online by Cambridge University Press:  28 July 2021

Prasenjit Barman*
Affiliation:
Geological Survey of India, Northern Region, Lucknow 226024, India , , , , , Centre of Advanced Study in Geology, Institute of Science, Banaras Hindu University (BHU), Varanasi 221005, India
Francisco Sánchez-Beristain
Affiliation:
Museo de Paleontología, Facultad de Ciencias, UNAM, Circuito Exterior S/N, Ciudad Universitaria, Coyoacán, 04510, CDMX, Mexico
Shruti Ranjan Mishra
Affiliation:
Geological Survey of India, Northern Region, Lucknow 226024, India , , , , ,
Mohd Ibrahim
Affiliation:
Geological Survey of India, Northern Region, Lucknow 226024, India , , , , ,
Narendra Kumar Swami
Affiliation:
Geological Survey of India, Northern Region, Lucknow 226024, India , , , , ,
Mukesh Bamniya
Affiliation:
Geological Survey of India, Northern Region, Lucknow 226024, India , , , , ,
Shailendra Singh
Affiliation:
Geological Survey of India, Northern Region, Lucknow 226024, India , , , , ,
*
*Corresponding author

Abstract

The Cretaceous chaetetid sponge Acanthochaetetes huauclillensis Sánchez-Beristain and García-Barrera is reported for the first time from the Aptian–Cenomanian Khalsi Formation, Ladakh Himalaya, India. Its low- to high-domical growth form could suggest an adaptation to either an environment with constant sedimentation rates, or to an irregular substrate. However, these growth forms also may indicate an absence of important environmental/sedimentological changes during the lifespan of the sponges. In addition, the growth form of this species suggests a calm, non-turbulent, reef-like microenvironment. Along with the other faunal assemblages, such as the rudists, corals, and the gastropod Nerinea, A. huauclillensis indicates a tropical to subtropical shallow marine carbonate platform setting. This new finding extends its stratigraphic range from the upper Hauterivian to the Aptian–Cenomanian interval in the eastern Tethyan realm.

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Articles
Copyright
Copyright © The Author(s), 2021. Published by Cambridge University Press on behalf of The Paleontological Society
Figure 0

Figure 1.Geological and location map of Khalsi area, Ladakh, India showing locations of Acanthochaetetes.

Figure 1

Figure 2.Lithological column of Khalsi Formation from where chaetetids have been recovered. Arrows mark Acanthochaetetes-bearing horizons.

Figure 2

Figure 3.Acanthochaetetes huauclillensis, Khalsi Formation. (1) Hand specimen showing well-preserved low domical growth form (destroyed during the preparation of thin sections); (2, 3) hand specimens showing high domical growth form (GSI-NRF-2/517, GSI-NRF-2/518). All scale bars 2 cm.

Figure 3

Figure 4.Photomicrographs of A. huauclillensis in transverse section (GSI-NRF-2/520). (1, 2) Note spines inside calicle lumen (white arrows) and the micritic? microstructure (black arrows); (3, 4) tubular thickenings accompanying tabulae (line segments) and spines (white arrows). See text for further details.

Figure 4

Figure 5.Photomicrographs of A. huauclillensis in longitudinal section (GSI-NRF-2/519), showing tabulae within each calicle. (1–4) Note the diagnostic scalariform (stair-like) disposition of tabulae in adjacent calicles (white arrows) as well as multiple calicle thickenings (black arrows). See text for further information.

Figure 5

Figure 6.Fauna associated with the A. huauclillensis, Khalsi Formation. (1, 2) Rudist; (3) ?Actinastrea sp.; (4) ?Nerinea texana.

Figure 6

Figure 7.Occurrence of extant Acanthochaetetes (summarized in Table 1).

Figure 7

Table 1.Global distribution of Acanthochaetetes of various ages.

Figure 8

Figure 8.Paleogeographic map for 120 Ma showing the reconstructed position of the locality (black star) of Acanthochaetetes huauclillensis from the Khalsi Formation, Ladakh India. The base map was generated using the ODSN Plate Tectonic Reconstruction Service (Hay et al., 1999, http://www.odsn.de/odsn/services/paleomap/paleomap.html).