Parasites are a big problem for avian medicine; some, such as protozoa, are microscopic and can infect wild and captive birds, causing diseases such as coccidiosis, lethal for domestic hens. By analyzing fossilized feces (known as coprolites), Brazilian paleontologists and parasitologists have discovered that birds were affected with similar parasites to those of today between 34 million and 23 million years ago in the region now known as Tremembé, state of São Paulo, as published in an April article in the International Journal of Paleopathology.
During this period, part of the Oligocene, the area which is now the Paraíba Valley was populated by large mammals (Pyrotheria), similar in appearance to the tapirs of today and hippopotami (Notoungulata), along with small animals such as rodents, bats, snakes, frogs, fish, and birds. Invisible to the naked eye, parasites such as protozoa thrived in the same environment, all inhabiting the waters or surrounding areas of a lake, which alternated between periods of drought and rainfall collection depending on the climate.
When these animals died or defecated, the organic material on the clayey soil was sometimes covered in new layers of the same sediment, forming rocks over millions of years. Under suitable conditions, such as a lack of oxygen and soil movement, some of the biological remains were fossilized.
The researchers used microscopes, lightly salinated liquids, and glycerine drops to analyze the samples, and were able to identify a significant amount of microorganisms. “We found 13 different morphological types; I never expected to see such quantity in paleontological material,” recalls paleoparasitologist Gustavo do Carmo, who conducted the research as part of his master’s at the Federal University of Juiz de Fora (UFJF), and is currently engaged in doctoral research at the Federal University of Minas Gerais (UFMG). The Taubaté catchment, home to the Tremembé formation, was discovered in the first half of the nineteenth century, and Carmo’s project was the first to study parasites of the past in Taubaté fossils.
The microorganisms were divided into two groups of protozoa: coccidia of the Eimeriidae family, and ameboids of the Archamoebae family. As the material was considerably degraded, and the parasitical forms not fully developed, it was not possible to identify the species.
These microorganisms, such as those from the Eimeriidae family, still cause health issues in animals. “Those of the genus Eimeria infect birds of all orders, and may cause coccidiosis; those of the Isospora genus are known for infecting caged birds, and go towards understanding the ecology of those in wild environments,” explains biologist Bruno Berto, of the Federal Rural University of Rio de Janeiro (UFRRJ), who coauthored the article. “Amoebas are less frequently seen in birds.”
Bird coprolite (white part) retains traces of parasitesGustavo do Carmo / UFMG
Due to its current relevance, the study is closely observed by veterinarians. “Identifying parasites with certain characteristics in ancestral birds, and analyzing how they fit into the evolutionary system may help in laboratory diagnosis and treatments today,” advocates Berto.
This was the first instance of protozoa recorded in coprolites from birds of the Brazilian Oligocene. Paleontologist and coprolite specialist Paula Dentzien Dias, of the Federal University of Rio Grande do Sul (UFRGS), who did not participate in the study, emphasizes the wealth of the material. “It is rare to find parasites in paleontological records; only in 2006 were eggs found in coprolites from Belgium,” she says. “The second discovery, in Rio Grande do Sul in 2013, was dated to the Brazilian Permian,” she adds, referring to the period between approximately 299 million and 252 million years ago.
This enabled scientists to better understand how parasites have evolved alongside birds. The amoeba discovered was primarily found in human beings, but the research demonstrated that it infected birds in the past. “Understanding the interactions of organisms and when certain groups acted as parasites in the past, and which animals were parasitized, is fundamental for comprehension of the evolution of species.”
The researchers also discovered that certain parasite characteristics evolved before they had first thought, such as the micropyle (a type of outlet valve in oocysts, the rounded structures where the infectious forms of parasites are formed) and the membrane on top of it, known as the polar cap.
In addition to their veterinary importance, these parasites play a central role in ecology. “They may interfere directly in reproduction among, or the feeding of, hosts,” says Carmo. The presence of infected birds, as indicated by the coprolites, shows that ancestral species from the Taubaté region contributed significantly to the proliferation of parasites in that period.
It was not possible to precisely pin down which bird species or groups were infected. Vultures, buzzards, and others similar in appearance to flamingos and hens are just some of those that occupied the region at the time. Another clue provided by the excrement is that the hosts were omnivores, feeding on a diet of fish, arthropods, and plants.
The aim now is to extend these diagnostics to gain a better understanding of the evolutionary history of the parasites. “We have already identified helminths at the same Tremembé site, and we are studying materials from other animals and regions, such as dinosaur coprolites from Minas Gerais,” concludes Carmo.
The story above was published with the title “Parasites of the Oligocene” in issue 343 of September/2024.
Scientific article
CARMO, G. M. et al. Protozoan parasites of birds from the Tremembé formation (Oligocene of the Taubaté Basin), São Paulo, Brazil. International Journal of Paleopathology. Vol. 45. Apr. 23, 2024.
