By B N KUMAR
The juveniles which must have left clutches soon after hatching, says the study published by PLOS.Org.
MUMBAI, Jan 21 (The CONNECT) - Researchers have found as many as 250 dinosaur eggs in 92 nesting sites of Narmada valley and they say the giant lizards lacked parental care.
“Parental care must have been absent as the size difference between juvenile and parent dinosaur is enormous and clutches are closely spaced,” says the study by geologist Harsha Dhiman of Delhi University and his team.
The finding also supports precocial behaviour of juveniles which must have left clutches soon after hatching. On the basis of abundant clutches, closely spaced clutches, similar eggs, and different oospecies, it is concluded that the titanosaurs of the study areas adopted for colonial nesting behavior, the report published by online science journal PLOS.Org.
Surprisingly, no osteological remains pertaining to embryo, juvenile, and parent dinosaurs have been found. This is perhaps because the dinosaurs did not live where they laid their eggs, or the osteological material is still unexposed or removed by erosion. The eggs are lacking embryos possibly because of their deep burial and modification due to plant root activity. The absence of juvenile skeletons may indicate their precocial behavior.
The study, “New Late Cretaceous titanosaur sauropod dinosaur egg clutches from lower Narmada valley, India: Palaeobiology and taphonomy” has been conducted by Dhiman and his team: Vishal Verma,Lourembam R. Singh,Vaibhav Miglani,Deepak Kumar Jha,Prasanta Sanyal,Sampat K. Tandon and Guntupalli V. R. Prasad.
Titanosaur is believed to have existed between around 144 and 65 million years ago.
“In addition, we made an attempt to infer aspects such as egg burial, absence of parental care, colonial nesting behavior. All the egg clutches were observed within sandy limestone and calcareous sandstone lithologies that occur in scattered outcrops with rocks showing floating siliciclastic grains in a micritic groundmass,” the report says.
Further, the presence of ferruginous sandstone in the Jamniapura and Padlya regions (Dhar District, central India) is indicative of a possible alluvial/fluvial setting. The presence of grainy intraclastic fabric, alveolar-septal fabrics, brecciation and shrinkage cracks observed in the clutch-bearing rocks are indicative of a low energy-low gradient palustrine depositional condition in a fluvial/alluvial setting.
Finally, we envisage that a few egg clutches of this area were laid close to lake/pond margins while most were laid away from the lake/pond margins, and thus, were hatched.
During the field investigations carried out between 2017 and 2020, the researchers found extensive hatcheries of dinosaurs in Bagh and Kukshi areas in Dhar District, M.P., notably from the villages Akhada, Dholiya Raipuriya, Jhaba, Jamniapura, and Padlya. This region falls in between the eastern most Lameta exposures at Jabalpur in upper Narmada valley (central India) and Balasinor in the west in lower Narmada valley (western central India). The Bagh-Kukshi area with many new nesting sites that have greater areal spread offer a fair amount of qualitative and quantitative nesting data.
Detailed field investigations were conducted in December 2017, January 2018 and March 2020 in the Dhar District, Madhya Pradesh, central India. The data with regards to nest type, number of eggs, diameter of eggs, egg-shape, egg-type, and pathology were collected as field observations related to egg clutches (Table 1). Additionally, along with the fossilized eggshells, specimens of host rocks of some of the egg clutches were also collected and data on their sedimentological characteristics was also recorded.
Peninsular India is well known for dinosaur oological fossils that occur at several sites in the Lameta Formation of central and western India, Deccan intertrappean beds, and shallow marine formations of the Cauvery Basin marking the extensive spread of the Indian dinosaur clutch, egg and eggshell sites [1–15]. From the Lameta Formation, dinosaur clutches, isolated eggs and eggshell fragments have been reported from the Lameta Ghat (type section), Bara Simla Hill, Chui Hill in Jabalpur, Bagh and Kukshi areas of Dhar District and Betul District of Madhya Pradesh (M.P.), Rahioli-Balasinor area of Gujarat, and Nand-Dongargaon Basin in Chandrapur District, Maharashtra.
Since the first report of dinosaur bones from the type locality near Jabalpur by Captain Sleeman in 1928, the Upper Cretaceous Lameta Formation has remained as an important source for well preserved and taxonomically identifiable dinosaur fossils which include both osteological and oological remains.