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Monolophosaurus jiangi
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Monolophosaurus (meaning "single-crested lizard" in reference to the holotype possessing a single crest on its skull) is a genus of tetanuran theropod dinosaur, possibly an allosauroid or a megalosauroid, from the Middle Jurassic Shishugou Formation in what is now Xinjiang, China. The holotype (IVPP 84019) was discovered in the Junggar Basin, in layers of the Wucaiwan Formation dating from the Oxfordian about 160 million years ago. It represents an adult or subadult individual, preserving everything except for the arms, legs, and most of the tail.
The animal's primary feature is a large single midline crest on its skull that extends from the premaxilla to the eye sockets, which was composed entirely of bone, highly pneumatic and very thin-walled. These traits of the crest suggest its use was not related to intraspecific or interspecific combat (where it might get bitten off or easily break with an action like a headbutt) but instead for a more non-violent purpose, such as species recognition or display. Because of the completeness of the holotype specimen, body size estimates can be made with a relatively high degree of confidence, despite the total length being unclear due to much of the tail being unpreserved. In 2016, Gregory S. Paul gave an estimate of 5.5 meters and 475 kg. At 80 centimeters in length, the skull was large for the animal's size, and was full of sharp, serrated teeth. The precaudal column was strongly built, making Monolophosaurus a relatively robust theropod. In the pelvis, the pubes and ischia contacted each other with a nearly vaulted closed underside. Its phylogenetic position has varied, with different studies suggesting allosauroid affinities, megalosauroid affinities, or affinities as a tetanuran more basal than both.
Monolophosaurus skull by Greg Paul.
 *This image is copyright of its original author Monolophosaurus skull from palaeos.com.  *This image is copyright of its original author Monolophosaurus by GetAwayTrike. (Note that the skull on this is undersized as it is not 80 cm long as per the most recent osteology in Brusatte et al. (2010), but it is otherwise good).  *This image is copyright of its original author Monolophosaurus from paulheaston.com.  *This image is copyright of its original author Monolophosaurus from dinosaursinart.com.  *This image is copyright of its original author Monolophosaurus mounted skeleton by Kabacchi.  *This image is copyright of its original author Monolophosaurus by Jordan Mallon.  *This image is copyright of its original author Monolophosaurus mounted skeleton by Yinan Chen.  *This image is copyright of its original author Monolophosaurus skull by Ghedoghedo.  *This image is copyright of its original author Monolophosaurus by Dotname2469.  *This image is copyright of its original author Monolophosaurus from Dinopedia.  *This image is copyright of its original author Monolophosaurus by Andrey Atuchin.  *This image is copyright of its original author
Similar to the post I made in the Yutyrannus profile, I find it plausible for Monolophosaurus to have fairly powerful jaws for its size (proportionally on par with T. rex in fact) from known data. How I reached this conclusion is as follows.
Estimating the bite force: I am not aware of any published bite force estimates for Monolophosaurus, so this estimate will be based on theropods with similarly-constructed skulls that do have published estimates (in this case, Allosaurus). An Allosaurus specimen with published figures for bite force is SMA 0005, with a bite force estimated at 8724 newtons. Based on the estimate in randomdinos' Allosaurus chart (I don't agree with all the estimates but have seen nothing wrong with the estimate for the specimen in question), it is 1600 kg, and has a skull 79 cm in length (this is stated in the comments of the chart). For comparison, the Monolophosaurus holotype (IVPP V84019) has an 80 cm long skull according to Page 3 of Brusatte et al. (2010), and Greg Paul (page 13) estimates it at 475 kg. With the skull from the skeletal reconstruction of SMA 0005 in Foth et al. (2015), it appears as though the skulls of SMA 0005 and IVPP V84019 are similar enough in build for their length to estimate the bite force of one by isometric scaling from the other. That gives us an estimate of 8946 newtons for the bite force of IVPP V84019 with this method (80/79 (8724)^2). Is this really indicating a bite force on par with T. rex for a given body size? As far as I can tell, if published bite force estimates for T. rex are accurate, it very much does indicate such. The same source for the bite force of SMA 0005 gives a bite force range of 35000-57000 newtons to T. rex specimen BHI 3033, with a mean of 46000 newtons. This specimen has been estimated to weigh 6500 kg by Asier Larramendi. For comparison, a hypothetical 6500 kg IVPP V84019 would have a bite force of 51226 newtons (6500/475 (8946)^0.667) if my estimates are correct, right on par with the given range for BHI 3033. |
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