Published today in Biological Reviews: "New perspectives on body size and shape evolution in dinosaurs" - the biggest paper from my PhD (my favourite chapter, too). https://doi.org/10.1111/brv.70026… Here's a thread outlining some of our key findings. (1/10)

A recent study from my lab group (Macaulay et al. 2023) looked at relationships between the dimensions of extant sauropsid skeletons & the soft tissues enveloping them, quantifying how much we need to expand skeleton-hugging volumes to match measured soft tissue volumes. (2/10)

If we assume that dinosaur soft tissues scaled in a comparable way to the extant animals phylogenetically bracketing them, these relationships provide a new way of estimating body segment mass properties in dinosaurs that is quantitatively grounded in empirical data. (3/10)

In the original study, these convex hull factors were applied to a selection of theropods to study proportional changes on the bird line. In our new paper, we took things further by estimating body dimensions in 52 dinosaurs, representing most major clades & body plans. (4/10)

Rather than only applying an "all bird" or "all reptile" approach to dinosaurs, we also explored "preferred" models that variably combined segments estimated from both. While this produces subjectively more realistic volumes, overall patterns between taxa are retained. (5/10)

We found that most of our mass estimates were greater than models in which soft tissue outlines adhered tightly to skeletons. I hope this will be a vindicating result for palaeoartists, as it adds quantitative support to the drive away from "shrink-wrapped" illustrations. (6/10)

Encouragingly, our mass ranges are mostly agreeable with those extrapolated from limb bone shafts, but there are points of variation. Many theropods appear to have slender limbs for their mass, whereas many ornithischians have seemingly robust limbs for their mass. (7/10)

An important take-home message is not to accept a single dinosaur mass estimate as a firm given. It's key to explore subjectivity/sensitivity in modelling approaches. Crucially, we should aim to evaluate that sensitivity within boundaries set by empirical biological data. (8/10)

Our methods also allow for a grounded look at relative body proportions, and how mass is distributed throughout the body. These plots show evolutionary patterns in how far the centre of mass was displaced from the hip. Dinosaur body shape evolution was a complicated web! (9/10)

There's a lot more in the paper, including extra context, spotlights on weird taxa (I talk about Acrocanthosaurus quite a lot), as well as outlines for future research directions, so I'd encourage people to have a dive! I'll highlight other key points in the coming days. (10/10)