Abstract Detail

Plants at the Cretaceous-Paleogene boundary

Matsunaga, Kelly [1], Manchester, Steven [2], Smith, Selena [3], Srivastava, Rashmi [4].

Fossil fruits from the Deccan Intertrappean Beds of India suggest a Late Cretaceous origin of borassoid palms and survival across the K-Pg boundary.

Plant fossils from the late Maastrichtian-early Danian Deccan Intertrappean Beds (DIB) of India provide valuable data for elucidating the evolutionary history of plant groups, testing biogeographic hypotheses, and understanding Indian biodiversity during the end-Cretaceous biotic crisis. Palms (Arecaceae) are particularly common within the Deccan plant fossil assemblages. These fossils, especially those of fruits, often preserve important characters necessary for placement below the family level and are therefore important for understanding the evolutionary history of palms. One species, represented by permineralized fruits, is known from at least six different localities of the DIB. These occurrences include localities that are late Maastrichtian in age, as well as those that are considered Danian, indicating that this palm species persisted through the K-Pg boundary in India. The fruits possess many taxonomically informative characters indicating affinities with the tribe Borasseae in subfamily Coryphoideae, including pericarp anatomy, embryo position, germination pores, carpel number, and position of stigmatic remains. However, modern palms comprise over 180 genera and are highly morphologically diverse, and thus determining precise systematic relationships of palm fossils is notoriously difficult using direct morphological comparisons. To augment our morphological observations and determine the precise relationships of the fossil, we performed genus-level phylogenetic analyses incorporating both DNA and morphological data using the software RAxML and MrBayes. All analyses strongly support placement of the fossils in the subtribe Hyphaeninae of tribe Borasseae (subfamily Coryphoideae). Members of tribe Borasseae are today found throughout the Indian Ocean region, including Madagascar, the Seychelles and Mascarene Islands, Africa, Arabia, India, and Southeast Asia. Our results indicate that borassoid palms evolved during the Late Cretaceous, much earlier than previously inferred from molecular clocks, have been present in the Indian Ocean region since at least the late Maastrichtian, and persisted through the end-Cretaceous extinction. These fossils have important implications for understanding the historical biogeography of Borasseae, the timing of evolutionary events within palms, and help us better understand how the K-Pg extinctions played out in India.

1 - University Of Michigan, Earth And Environmental Sciences, 1100 N University Ave, 2534 CC Little Bldg, Ann Arbor, MI, 48109, United States
2 - Florida Museum Of Natural History, Po Box 117800, Gainesville, FL, 32611, United States
3 - Department Of Earth & Environmental Sciences, 1100 North University Avenue, 2534 CC Little Building, Ann Arbor, MI, 48109, United States
4 - Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow, India

Keywords:
fossil
palm
Arecaceae
fruit
India
Deccan
K-Pg
Phylogenetics.

Presentation Type: Colloquium Presentations
Session: C01, Plants at the Cretaceous-Paleogene boundary
Location: 101/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 11:00 AM
Number: C01009
Abstract ID:566
Candidate for Awards:None