[Paleontology • 2023] Alligator munensis อัลลิเกเตอร์ มูลเอนซิส • An Extinct Deep-snouted Alligator Species from the Quaternary of Thailand and Comments on the Evolution of Ccrushing Dentition in alligatorids

Alligator munensis

 Darlim, Suraprasit, Chaimanee, Tian, Yamee, Rugbumrung, Kaweera & Rabi, 2023

อัลลิเกเตอร์ มูลเอนซิส | อัลลิเกเตอร์แม่น้ำมูล ||  DOI: 10.1038/s41598-023-36559-6

 Art by Márton Szabó. 

Abstract

Fossil Alligator remains from Asia are critical for tracing the enigmatic evolutionary origin of the Chinese alligator, Alligator sinensis, the only living representative of Alligatoridae outside the New World. The Asian fossil record is extremely scarce and it remains unknown whether A. sinensis is an anagenetic lineage or alternatively, extinct divergent species were once present. We provide a detailed comparative description of a morphologically highly distinct Alligator skull from the Quaternary of Thailand. Several autapomorphic characters warrant the designation of a new species. Alligator munensis sp. nov. shares obvious derived features with A. sinensis but autapomorphies imply a cladogenetic split, possibly driven by the uplift of the southeastern Tibetan plateau. The presence of enlarged posterior alveoli in Alligator munensis is most consistent with a reversal to the alligatorine ancestral condition of having crushing dentition, a morphology strikingly absent among living alligatorids. Crushing dentition has been previously considered to indicate an ecological specialisation in early alligatorines that was subsequently lost in Alligator spp. However, we argue that there is yet no evidence for crushing dentition reflecting an adaptation for a narrower niche, while opportunistic feeding, including seasonal utilisation of hard-shelled preys, is a reasonable alternative interpretation of its function.

  

  

 Alligator munensis sp. nov. 

อัลลิเกเตอร์ มูลเอนซิส - อัลลิเกเตอร์แม่น้ำมูล

 

Virtual representation of Alligator munensis sp. nov. holotype (DMR-BSL-2011-2).
 (a) Digital reconstruction and (b) artistic reconstruction, both in left lateral views.

 Art by Márton Szabó. Scale bar: 10 cm.

Gustavo Darlim, Kantapon Suraprasit, Yaowalak Chaimanee, Pannipa Tian, Chotima Yamee, Mana Rugbumrung, Adulwit Kaweera and Márton Rabi. 2023. An Extinct Deep-snouted Alligator Species from the Quaternary of Thailand and Comments on the Evolution of Ccrushing Dentition in alligatorids. Scientific Reports. 13: 10406. DOI: 10.1038/s41598-023-36559-6

[Herpetology • 2017] Extension of the Geographical Distribution of Schneider’s Dwarf Caiman, Paleosuchus trigonatus (Schneider, 1801) (Crocodylia: Alligatoridae), in the Amazon–Cerrado Transition, Brazil

Male Paleosuchus trigonatus captured in Claro River

(Campos, Muniz & Magnusson, 2017) 

 DOI:  10.15560/13.4.91

Abstract

We present new records of occurrence of Schneider’s Dwarf Caiman, Paleosuchus trigonatus and extend its geographical distribution. Eight individuals were caught in the following locations: Sangue River, in the municipality of Campo Novo dos Parecis, Claro River and Marapi River, in the municipality of São José do Rio Claro, and tributaries of the Juruena River, in the state of Mato Grosso, Brazil. These records extend the geographical distribution of the species nearly 500 km south of the limit given in published range maps.

Keywords: New records; conservation; Paleosuchus; Mato Grosso; Brazilian Amazon

Figure 1. Male specimen of Paleosuchus trigonatus captured in Claro River, showing some diagnostic characters.
A. General view of the body. B. Head shape. C. Arrow indicates the two scales of the sacral region. D. Post-occipital region.

Figure 3. New records of the geographic distribution of Paleosuchus trigonatus in the Sangue, Claro, Marapi and Alegre rivers in the Cerrado biome, Mato Grosso, Brazil. Triangle = 8 individuals captured; inverted triangle = 3 individuals observed and not captured.

 Zilca Campos, Fábio Muniz and William E Magnusson. 2017. Extension of the Geographical Distribution of Schneider’s Dwarf Caiman, Paleosuchus trigonatus (Schneider, 1801) (Crocodylia: Alligatoridae), in the Amazon–Cerrado Transition, Brazil.
 Check List. 13(4); 91-94.  DOI:  10.15560/13.4.91

ResearchGate.net/publication/318417116_Extension_of_the_geographical_distribution_of_Schneider's_Dwarf_Caiman_Paleosuchus_trigonatus_Schneider_1801_Crocodylia_Alligatoridae_in_the_Amazon-Cerrado_transition_Brazil