For inducing fear and unease, dead things are big-time spooky. Geological factors can result in recording death in particularly captivating ways, freezing the animals’ death throes across enormous stretches of time. Preservation can mean bones replaced by mineralization to give us skeletal remains, impressions in fine sediment retaining incredible detail, or entire animals trapped in the resin of a tree, that later hardens into a transparent time capsule. Some amazing fossils and preserved carcasses tell us not only how these animals died, but also about how they lived.
The earth doesn’t care about us or other life forms on it. Death is part of life and probably shouldn’t freak us out as much as it often seems to. (An example is the hubbub and outrage over the #bestcarcass tag on Twitter, it’s pretty educational. OK, not so “pretty” but still educational.) Remnants of death provide us with extremely valuable information about how an animal LIVED.
And there can be examples of exquisite beauty. This mouse died in a copper mine where the minerals chalcanthite (hydrated copper sulfate) and atacamite (copper chloride hydroxide) crystals have grown on the hair of the carcass like rock candy on string. This specimen belongs to the Fersman Mineralogical museum in Russia.
This spectacular fossil (featured on #bestcarcass) shows a fatal encounter between a fish-eating pterosaur and a pterosaur-eating fish. [A small Rhamphorynchus was in the act of swallowing a small fish when it was attacked by a large gar-like fish called Aspidorhynchus. The fish could not swallow the winged reptile for reasons unknown and failed to free itself from the ill-chosen meal.
The violent death scene is described by authors Frey & Tischlinger (PLOS One, 2012):
That the fish, in fact, tried to get rid of the pterosaur by vigorous movements of its head is evidenced by the distortion of the left wing finger elements, while the remaining skeleton of the Rhamphorhynchus lies in natural articulation. Apparently, the flight membrane tissue remained jammed between the teeth, while the interphalangeal ligaments of the left wing finger ruptured under the power of the fish tearing at the flight membrane. Finally, the entire wing finger of the drowned pterosaur was pulled under the antebrachium. Such a distortion can only happen when the proximal part of the flight membrane, likely the thin and structurally weak tenopatagium, was dramatically overextended or even had ruptured. The most likely scenario is that the Aspidorhynchus fought its victim for a period of time, thereby rapidly sinking into the hostile anoxic water layer of the Late Jurassic Eichstätt basin, where it was instantly suffocated. Still linked together, both carcasses sank to the sea floor, whereby the pterosaur contacted the ground first, likely being pushed down by the massive head of the Aspidorhynchus.
The fine sediment in this area became the Solnhofen limestone of Bavaria that provided us with many other astounding fossils, including Archaeopteryx.
Another famous fossil that tells a harrowing story is that of Oviraptor (egg-stealer), so named because of this particular fossil that was found associated with a clutch of eggs. Scientists at the time interpreted the dinosaur to be stealing the eggs to eat when the thief and nest were buried and preserved. The more dramatic truth was revealed when it was later confirmed that the eggs belonged to the Oviraptor who was guarding them when death descended upon the brood.
A maternal moment was paused at a critical time as a mother ichthyosaur is forever in labor as she died during birth of her offspring. There are at least two other babies associated with this fossil – one outside and another still unborn. The mother could also have died first and the young were spontaneously aborted. (There are no good pictures of the entire fossil but see another example below.)
Two other carcasses were preserved as evidence of mortal combat. A Velociraptor (predator) and Protoceratops (prey) preserved together show evidence of broken bones. It is unknown if one or both of the animals were alive at burial or recently deceased from their encounter. A similar scene depicts a Nanotyrannus and a Triceratops.
Just like two deer who die with their antlers entangled, a pair of mammoths collapsed head to head with their tusks lodged together. A wolf had been pinned underneath the carcasses.
A particularly disturbing scene is that of a mass death. In some cases, the remains will be covered by sediment and preserved. From these incidents, we know that some dinosaurs traveled in herds, like wildebeest. Washed away by a swollen river, their bodies were buried and excavated millions of years later in a mass of bones.
The Hilda mega bone bed in Dinosaur Provincial Park, Alberta, Canada is the location of where a great herd of Centrosaurs died en masse either by trying to cross a raging river, or drowning in a flood [artist’s depiction here]. The dense collection of bones is estimated to be those of 667 individuals killed at the same time. Creationists love this example of mass death attributed to a flood and use it to further their “great world flood” catastrophe. Instead of proof of a Biblical myth, this example shows us that these animals stayed together in these large herd sizes where ages and sizes varied. There are several examples of localized flooding, but in this case, the sediment buried the unfortunate victims of the raging storm.
Catastrophists like Velikovsky and Donnelly pointed out mass bone beds as further evidence of sudden earth events. Fish fossils are found in what appear to have been massive shoals. An Upper Miocene strata in Algeria consisting of deep and shallow water fish and diatoms was interpreted as being the result of a volcanic event (1933, Journal of Geology) An amphibian graveyard in New Mexico may represent the mass death of animals that congregated around the last remaining water in a time of drought (1939, Scientific Monthly and Science News Letter). 
Kirkland, et al. (2016) described a mass death assemblage of well-preserved Utahraptors fossils, found in a sandstone sill, that they interpreted as resulting from “quicksand”. The original ground was oversaturated sand possibly fed by artesian springs exerting upward pressure. Small animals could run across it. Large animals that stood on it would become trapped, sinking into the liquid sand burying them deeper and deeper.
A similar situation occurred in another geologically deadly place that gave scientists a comprehensive catalog of past life in an area now completely different – LaBrea Tar Pits in downtown Los Angeles. The pits were a death trap for animals during the Pleistocene who came to drink the water off the surface in the dry climate only to get stuck in the thick sticky ooze welling up from the oil deposits below. The prey animals would be slowed down or trapped by the few inches of natural asphalt springs. Predators would come along and feast. A huge diversity of animals and plants have been recovered from the LaBrea deposits. Animal collections contain thousands of fossils from the same species across all ages. Some have spectacular degrees of preservation such as bones that include fossilized blowfly larva, and plant fragments remaining between the teeth . Smelling of hydrocarbons, with fresh black seeps marked by orange caution cones along the park path, and some of the millions of bones on display, the LaBrea pits remain a spooky place even under the gorgeous California sun.
Twelve million years ago, in Nebraska, horses, camels, and rhinos, adults and babies, perished together in a water hole after volcanic ash billowed in suffocating them. Now designated Ashfall Fossil Beds park, a park official called it “a very graphic display” as some rhinos have unborn young inside.
This scene of animal mass death is echoed in one of the most famously preserved human mass death locations – the ancient city of Pompeii, Italy when Mt. Vesuvius buried towns in ash 25 m thick. When the volcano erupted in 79 AD, most townspeople had left. The explosion caused utter darkness and sent searing hot gas, ash fragments, and pulverized rock dust rocketing over land enveloping the escaping residents including mothers, children, pets and livestock. The heat of the surge killed them instantly. The dense, moistureless burial conditions caused imprinting of fine details into the deposit and hid the streets, buildings, and art of the age until they were rediscovered in 1748. A technique called the Fiorelli process was used whereby plaster was poured into cavities in the ash where the bodies had once been before decaying away. The result were the incredibly spooky death poses of those who perished in the cataclysm.
The Earth takes away, and sometimes, it gives.
1. W.R. Corliss, Neglected Geological Anomalies, 1990, The Sourcebook Project. p. 86-87.
2. J.M. Harris (ed), Rancho La Brea: Death Trap and Treasure Trove, 2010, Los Angeles County Museum of Natural History Foundation.
Putrid pit of dinosaur corpses
Stop eating before you read this part. It’s a bit stomach-turning. A recent find of a fossilized death assemblage tells a graphic story of mass death.
The Cleveland-Lloyd Dinosaur Quarry is a dense deposit of Jurassic-age theropod dinosaurs, mostly Allosaurus fragilis. What caused this mass death of 46 allosaurs (and some 25 other dinosaurs)? Why were there so few other kinds of typical fossils like crocodilian teeth or turtle shells? The bones were not scavenged. What happened here?
Hypotheses included that the place was a death trap where animals became mired in mud. Or, that the animals were killed by some toxin in the environment. A recent study suggests that the location was an ephemeral water body that was the final resting place for animals that died nearby.
Periodic floods washed the corpses into this low area creating, as the author describe, “significant numbers of rotting dinosaurs in a body of standing water” creating “hypereutrophic” conditions. Yuck!
This hypothesis explains the accumulation and condition of the remains and why there are few other vertebrate remains present. Additional evidence to support this putrid pond idea are as follows:
Sediment geochemistry. The deposition area is enriched in heavy metals and sulfide minerals which are not present in the surrounding formation or in other fossil bone beds. The presence of sulfides and calcite/barite nodules suggest that hypereutrophic conditions were present resulting in a concentration of heavy metals as the animals decomposed.
High rates of organic matter decay would have led to hypoxia or anoxia and the subsequent formation of sulfide minerals and the calcareous soaps required to form the calcite nodules.
Bone fragment abrasion patterns. Characteristics of the bone fragments in the quarry deposit were compared to other bone assemblages. There was a wide range of degree of abrasion in this particular quarry. Some bones had been exposed to environmental weathering longer than others. This variation, along with an examination of the matrix within which the larger bones were fossilized, supports the idea that there were separate events that formed the deposit as periodic flooding and drying occurred, possibly over a range of 10-20 years.
The physical characteristics of the bone fragments of CLDQ suggest variable taphonomic histories among the fragments; angular fragments suggest weathering or pulverization followed immediately by burial while rounded fragments suggest prolonged exposure and re-working.
Finally, using the evidence about the climate conditions of the time, it appears that this area in Utah was subjected to periods of dryness interspersed with “weak monsoons and sub-humid conditions during stronger monsoons, similar to climates seen in modern savannahs”. This supports the idea that the carcasses accumulated during flood events and then periodically dried out, leaving a horrible pit of rotting flesh in a toxic pool.
Read the entire study here:
New data towards the development of a comprehensive taphonomic framework for the Late Jurassic Cleveland-Lloyd Dinosaur Quarry, Central Utah by Joseph E. Peterson , Jonathan P. Warnock, Shawn L. Eberhart, Steven R. Clawson, and Christopher R. Noto
published June 6, 2017. PeerJ.