Friday, November 23, 2018

[Paleontology • 2019] Lisowicia bojani • An Elephant-sized Late Triassic Synapsid with Erect Limbs

Lisowicia bojani 
Sulej & Niedźwiedzki, 2018

Here, we describe the dicynodont Lisowicia bojani, from the Late Triassic of Poland, a gigantic synapsid with seemingly upright subcursorial limbs that reached an estimated length of more than 4.5 meters, height of 2.6 meters, and body mass of 9 tons. Lisowicia is the youngest undisputed dicynodont and the largest nondinosaurian terrestrial tetrapod from the Triassic. The lack of lines of arrested growth and the highly remodeled cortex of its limb bones suggest permanently rapid growth and recalls that of dinosaurs and mammals. The discovery of Lisowicia overturns the established picture of the Triassic megaherbivore radiation as a phenomenon restricted to dinosaurs and shows that stem-group mammals were capable of reaching body sizes that were not attained again in mammalian evolution until the latest Eocene.

Illustration: Julius Csotonyi 

Lisowicia bojani gen. et sp. nov., hind limb elements (femur, fibula, tibia) preserved in situ, upper bone-bearing interval, Lipie Śląskie clay-pit at Lisowice.

Artistic reconstruction of Lisowicia bojani, front view.
Illustration: Karolina Suchan-Okulska

Systematic paleontology
 Synapsida Osborn, 1903 
Therapsida Broom, 1905 
Anomodontia Owen, 1860 
Dicynodontia Owen, 1860 
Placeriinae King, 1988 

Lisowicia gen. nov. 

Type species. Lisowicia bojani sp. nov.

Diagnosis. The dicynodont differs from all other dicynodonts as it possesses the following unique combination of character states, visible in the holotype (ZPAL V.33/96, left humerus): 1) the humerus has a narrower entepicondyle in comparison with other dicynodonts (autapomorphy); 2) the entepicondylar foramen of the humerus is absent (autapomorphy); 3) the supinator process is longer (it is 31% of the total humerus length) than in other dicynodonts. 

Lisowicia bojani sp. nov. 

Etymology. Lisowicia, from the name of the village Lisowice where the bones were found; bojani, in honor of Ludwig Heinrich Bojanus (1776–1827), comparative anatomist and paleontologist.

Age. Late Norian-earliest Rhaetian, Late Triassic.

Tomasz Sulej and Grzegorz Niedźwiedzki. 2018. An Elephant-sized Late Triassic Synapsid with Erect Limbs. Science. 363(6422); 78-80.  DOI:  10.1126/science.aal4853

Scientists find remains of huge ancient herbivore via @physorg_com