Dinosaurs and Parental Care
1. The word “alleged” in the passage is closet in meaning to
2. Paragraph 1 answers which of the following questions about parental care in dinosaurs?
A.Which type of parental care was more important for the survival of dinosaur young,prehatching care or posthatching care?
B.Why were dinosaur remains in eastern Montana preserved rather than destroyed over time?
C.Did Maiasaura hadrosaurs provide types of parental care not provided by other dinosaurs?
D.What evidence supports the view that Maiasaura females laid their eggs in nests?
From fossil evidence alone the question of whether or not dinosaurs cared for their young is very difficult to answer. Because behaviors are not preserved in the fossil record, we can only make inferences from indirect evidence. Parental care can be divided into two types of behavior: prehatching (building nests and incubating eggs—for example, sitting on top of them so as to warm the eggs and encourage hatching) and posthatching (feeding the young and guarding the nests). Most of our evidence comes from alleged dinosaur rookeries (places where nests are built). Several have been excavated in eastern Montana, where a large concentration of dinosaur nests was found at a place now called Egg Mountain. Most of these probably belonged to the hadrosaur Maiasaura. Preserved in these nests are the bones of baby dinosaurs. The finds at Egg Mountain and other sites around the world document that dinosaurs laid their eggs in nests.
The nests at Egg Mountain are reported to be equally spaced, separated by a space corresponding to the length of an adult Maiasaura. From this arrangement scientists have inferred that the nests were separated in this way to allow incubation in a tightly packed nesting colony. Although this interpretation is open to challenge, the discovery of Oviraplor adults on top of Oviraplor egg clutches (as determined by embryos in some eggs), is relatively powerful evidence that at least these dinosaurs incubated their nests.
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