Hatching Asynchrony in Oviraptorid Dinosaurs Sheds Light on Their Unique Nesting Biology

Synopsis Dinosaur nesting biology has been an intriguing research topic, though dinosaur behaviors were relatively less illuminated because of the constraints of the fossil record. For instance, hatching asynchrony, where eggs in a single clutch hatch at different times, is unique to modern neoavian birds but was also suggested to be present in oviraptorid dinosaurs based on a possible partial clutch of four embryo-containing eggs from Mongolia. Unfortunately, unequivocal evidence for the origination of these eggs from a single clutch is lacking. Here we report a new, better preserved partial oviraptorid clutch with three embryo-containing eggs—a single egg (Egg I) and a pair (Egg II/III)—from the Late Cretaceous Nanxiong Group of Jiangxi Province, China. Geopetal features indicate that the pair of eggs was laid prior to the single egg. Neutron tomographic images in combination with osteological features indicate that the embryo of the single egg is less developed than those of the paired eggs. Eggshell histology suggests that the embryo-induced erosion in the paired eggs is markedly more pronounced than in the single egg, providing a new line of evidence for hatching asynchrony. The inferred hatching asynchrony in combination with previously surmised thermoregulatory incubation and communal nesting behaviors very likely suggests that oviraptorid dinosaurs presented a unique reproductive biology lacking modern analogs, which is contrary to the predominant view that their reproductive biology was intermediate between that of modern crocodiles and birds.

A UHF RFID System for Studying Individual Feeding and Nesting Behaviors of Group-Housed Laying Hens

Enriched colony housing (ECH) is a relatively new egg production system. As such, information is lacking on design parameters to ensure the well-being of the hens and optimal utilization of housing resources. A new system has been developed at Iowa State University that enables automated monitoring and quantification of feeding and nesting behaviors of individual hens in ECH. Ultra-high-frequency radio frequency identification (UHF RFID) is employed to track individual animals. The UHF RFID system consists of four components: antennas, tags, readers, and a data acquisition system. The antennas for monitoring feeding behavior are placed inside the two feed troughs and covered with plastic boards. Each feed trough has six antennas aligned in series covering the length of the feeder. Four additional antennas are placed inside the nest boxes to monitor the nesting behaviors. All 16 antennas are connected to five 4-channel readers, two per feed trough and one for the nest boxes, that are further connected to the hosting computer via Ethernet. Feed and water consumption and egg production are continuously monitored using load cells. This article describes the development and testing of the RFID system for monitoring feeding and nesting behaviors and provides sample data. The system has proven to be able to characterize benchmark feeding and nesting behaviors of individual hens in ECH, such as daily time spent at the feeder and in the nest box, daily frequency of visiting the feeder and the nest box, number of hens feeding and nesting simultaneously, and variability in these behaviors among individual hens. Future applications of the system include assessing the impact of resource allocation and management practices on feeding and nesting behaviors and on the well-being of the hens. This information will provide a scientific basis for optimal design and management of alternative hen housing systems. Keywords: Animal well-being, Enriched colony housing, Feeding behavior, Nesting behavior, UHF RFID.

What do giant titanosaur dinosaurs and modern Australasian megapodes have in common?

Titanosauria is a globally distributed clade of sometimes extremely large Mesozoic herbivorous sauropod dinosaurs. On the basis of current evidence these giant dinosaurs seem to have reproduced in specific and localized nesting sites. However, no investigations have been performed to understand the possible ecological and geological biases that acted for the selection of these nesting sites worldwide. In this study, observations were performed on the best-known Cretaceous nesting sites around the world. Our observations strongly suggest their eggs were incubated with environmental sources of heat, in burial conditions. Taking into account the clutch composition and geometry, the nature and properties of the sediments, the eggshells’ structures and conductance, it would appear that titanosaurs adopted nesting behaviors comparable to the modern Australasian megapodes, using burrow-nesting in diverse media and mound-building strategies.