Laevisuchus

Not to be confused with Lewisuchus.

Laevisuchus (/ˌlɛvɪˈsjuːkəs/, "light crocodile") is a genus of theropod dinosaur from the Late Cretaceous. Its remains were discovered by Charles Alfred Matley near Jabalpur in Maastrichtian "Carnosaur Bed" deposits in the Lameta Formation in Madhya Pradesh, central India, and were named and described by paleontologists Friedrich von Huene and Matley in 1933.^[2]

Laevisuchus Temporal range: Maastrichtian, 70–66 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓ [1]
Cervical vertebra K20/613 in multiple views
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Family:	†Noasauridae
Genus:	†Laevisuchus Huene & Matley, 1933
Type species
†Laevisuchus indicus Huene & Matley, 1933
Synonyms
Jubbulpuria tenuis? Huene & Matley, 1933

The type species is Laevisuchus indicus. The generic name is derived from Latin laevis, "light" and the Greek name for the ancient Egyptian crocodile god, Soukhos. The specific name means "Indian" in Latin. It is known only from three cervical vertebrae (GSI K20/613, GSI K20/614, and GSI K27/696) and a dorsal vertebra (GSI K27/588). A holotype was not assigned by Huene and Matley, and a lectotype has never been chosen from the syntypes. All remains except GSI K27/696 were lost, though GSI K20/613 was rediscovered in 2012.^[3][4] A 2024 revision of the small-bodied theropods from India classified Jubbulpuria tenuis as a junior synonym of Laevisuchus, and suggested that other taxa (Compsosuchus solus and Ornithomimoides? barasimlensis) are likely indeterminate abelisaurs.^[4]

Laevisuchus type locality in Carnosaur beds, Bara Simla, Jabalpur, Madhya Pradesh, India

Description

Laevisuchus was a small bipedal carnivore about the same size as Masiakasaurus, which is estimated to be around 2 metres (6.6 ft) in length.^[4] It was described on the basis of cervical (GSI K20/614, GSI K20/613, GSI K27/696) and dorsal vertebrae (GSI K27/588), being distinguished by blunt pre- and postzygapophyses, shorter proportions, and a central neural spine position in dorsal view, unlike the relative Masiakasaurus. Its broader neural arch and deeper incisions in spinopostzygapophyseal laminae differentiate it from Noasaurus.^[4] GSI K27/696 features a neural arch significantly broader and longer than the centrum, creating a top-heavy look. Pneumatopores on its sides and uneven joint surfaces accentuate this look, while pronounced parapophyses suggest ventral expansion. The referred caudal vertebrae GSI K20/612 and GSI K27/614 (Jubbulpuria) are similar in size and shape, potentially from the same Laevisuchus specimen. The former lacks features such as the transverse processes and neural spine, and the latter is slightly stouter, indicating a more proximal tail position.^[4] A partial right dentary RTMNU/DG/VERT/1/55P/2020, shares features with the noasaurid Masiakasaurus, and, while it wasn't formally referred to as Laevisuchus, it was suggested to come from it or a related form.^[4]

Jubbulpuria vertebrae, now referred to Laevisuchus

Classification

Life restoration of Laevisuchus (lower right) with contemporary dinosaurs

Laevisuchus was originally classified by Huene as a "coelurid" due to the similarity of its vertebrae with those of the Coelurosaur Aristosuchus. However, an analysis in 2004 has shown it to be an abelisauroid because of its long epipophyses, a pair of foramina on the centrum, and low and triangular neural spines. The vertebrae specifically resemble those of noasaurids like Masiakasaurus and Noasaurus due to having more anteriorly placed neural spines and posteriorly reduced epipophyses.^[5][6] The Jubbulpuria material was originally classified by Huene as another "coelurid" similar to but smaller than Coeluroides, another poorly known theropod from the Lameta Formation.^[7]

In 2024, Laevisuchus was recovered as a member of the Noasauridae, in an unresolved position outside the clade that includes Masiakasaurus and Noasaurus. Jubbulpuria was also considered a possible synonym of Laevisuchus.^[4]

See also

• Dinosaurs portal

• Timeline of ceratosaur research
• Jubbulpuria

References

1. Mohabey, Dhananjay M.; Samant, Bandana (2 April 2015). "Deccan Continental Flood Basalt Eruption Terminated Indian Dinosaurs before the Cretaceous-Paleogene Boundary". Paleontology. Geological Society of India. pp. 260–267. doi:10.17491/cgsi/2013/63310. ISBN 978-93-80998-08-4.
2. F. v. Huene and C. A. Matley, 1933, "The Cretaceous Saurischia and Ornithischia of the Central Provinces of India", Palaeontologica Indica (New Series), Memoirs of the Geological Survey of India 21(1): 1-74
3. Mohabey, Dhananjay M.; Sen, Subhasis; Wilson, Jeffrey A. (2013). "India's first dinosaur, rediscovered" (PDF). Current Science. 104 (1): 34–37.
4. Mohabey, Dhananjay M.; Samant, Bandana; Vélez-Rosado, Kevin I.; Wilson Mantilla, Jeffrey A. (7 February 2024). "A review of small-bodied theropod dinosaurs from the Upper Cretaceous of India, with description of new cranial remains of a noasaurid (Theropoda: Abelisauria)". Journal of Vertebrate Paleontology. doi:10.1080/02724634.2023.2288088. ISSN 0272-4634.
5. Tykoski, R.S. & Rowe, T. (2004). "Ceratosauria". In: Weishampel, D.B., Dodson, P., & Osmolska, H. (Eds.) The Dinosauria (2nd edition). Berkeley: University of California Press. Pp. 47–70 ISBN 0-520-24209-2
6. Novas, Fernando; Agnolin, Federico; Bandyopadhyay, Saswati (2004). "Cretaceous theropods from India: A review of specimens described by Huene and Matley (1933)". Revista del Museo Argentino de Ciencias Naturales, nuevo serie. 6 (1): 67–103. doi:10.22179/REVMACN.6.74.
7. Huene, F. von (1932). "Die fossile Reptil-Ordnung Saurischia, ihre Entwicklung und Geschichte: Monographien zur Geologie und Palaeontologie". 1e Serie, Heft 4: 1–361. Retrieved 8 February 2024.