Selves Portrait 2: Parasitism

By Sue Lawton and Ven Loetz

Earlier this year we took a “field” trip to another museum. Which is to say we took a trip to The Field Museum in Chicago. This is obviously a much bigger and more famous museum than the MPM, although their pelican diorama was paltry in comparison to Milwaukee’s.  So small and not nearly enough pelicans! A cormorant or two filled things out around the edges.

Taxidermy pelicans and cormorant in a diorama at the Field Museum in Chicago

The Field’s Evolving Planet exhibit, however, is bonkers huge with almost too much to look at in one day. We drooled over ichthyosaur skulls and delicately prepared trilobites with spiny protrusions. We saw Dimetrodon and Megaloceros, and of course, dinosaurs. So many dinosaurs! If there is one thing I’d like to see more of in the new MPM, it’s dino skeletons. The dinosaurs in the Field are set in a large hall amidst historical paleoart murals by Charles Knight.

A Megaloceros skeleton posed in front of a paleo art mural by Charles Knight (left) Dimetrodon, who was a Permian synapsid and NOT a dinosaur (right)

The famous celebrity skeleton of the collection is undoubtedly Sue the T. rex. They have their own dedicated room with a light display and narration that showcases details of Sue’s skeleton and what scientists have been able to learn from it. A spot light trains on Sue’s broken-and-healed ribs, and their arthritic legs. The gastralia (ribs covering the stomach area) give a much more barrel-shaped physique than the shrink-wrapped paleo art tyrannosaurus of my childhood. Sue was an absolute beast!

But the skull on that skeletal mount is a cast. The real skull is in its own separate case so that visitors can get up close and researchers can have easier access. Sue’s real skull is gnarled and smushed-looking, and at eye-level it’s apparent how truly gargantuan this animal was. The left lower jaw is full of holes and the signage describes how they resemble holes made by modern avian parasites such as Trichomonsis gallinae. It’s possible Sue died of a parasitic infection.

While this was a really compelling idea (and inspired my artwork), the day I went to make this blog post, the Field Museum posted an update; after examining the skull, paleontologist Jingmai O’ Conner now proposes that it does not appear consistent with a parasitic infection. Science is a complex and ever evolving process and one researcher may make observations missed by another. The holes, it would seem, remain a mystery! For the purposes of my artwork, and the usual course of all paleoart, it now serves as an outdated marker of a former hypothesis.

Sue the T. rex’s skeleton with a skull replica (left) Sue’s actual fossil skull and jaw full of mysterious holes (right)

The first “Selves Portrait” was based on the concept of symbiosis. But what happens when entangled organisms don’t get along so well? When one life takes more than it gives? As a non-binary Sue with a chronic illness, this “very dead” tyrant speaks to me in a strange way. With things like long covid, an invading organism takes root and continues to eat away from the inside. With autoimmune diseases, however, the “enemy” is the self, fighting a non-existent or long-gone foe. The internal ecosystem becomes unbalanced and feels more than a little unfair. One of my two teenagers also suffers from autoimmune diseases and is named Ash, so Sue the T.rex and the Ash tree became the key organisms at play in this piece. Trichomonsis gallinae and the emerald ash borer beetle eat their hosts from the inside wreaking havoc and internal damage until the pain is too visible to ignore. Where is the boundary between self and non-self? The immune system, as it turns out, isn’t always great at sorting that out. And with human microbiomes in decline, they might be missing some symbiotic or neutral friends that used to participate in the balancing act. Interestingly, the emerald ash borer beetle doesn’t actually digest the wood it consumes; it requires a partner — a fungus that the beetle leaves in packets for its larvae. The fungus allows the larvae to tunnel out their elaborate labyrinths beneath the bark, eating their way to adulthood. The US has experimented with using multiple species of parasitoid wasps to control emerald ash borers. The one pictured here is Spathius galinae, a native of Russia. In Asia, where the ash borer beetles are from, the Ash trees and beetles live in balance, with the trees having developed some protective traits and the local wasps parasitizing many more. Sometimes you need a parasite to deal with your parasites.

Details from “Selves Portrait 2” show a trichomonsis parasite, an infected jaw, emerald ash borer beetles, and the hope of a tiny parasitoid wasp

It’s unknown what ghosts Sue the T. rex battled, but we do know Sue carried the damage within their body, a fossilization of trauma. I sometimes try to imagine what stories our own fossils might tell a scientist far in the future. Will they know how we struggled to manage internal balance, both physically and mentally? Will they see all the selves inside us and how to we tried to keep them from eating us away? How do we calm the friendly fire and still keep the invaders at bay? Many stories will go untold, decaying back into the environment to feed the funguses and worms and plants, while others will turn to stone, a record of the search for balance. The process is so complicated and hard, but there is beauty in the mess and the detangling of the threads. The aftermath can either turn to stone or into symbiotic lichens to feed countless other lives to come.