Palaelodidae

Palaelodidae is a family of extinct birds that belonged to the same group as modern flamingos. These birds lived during a time called the Neogene, and their fossils have been found on every continent except Antarctica. The oldest fossils of these birds were discovered in Egypt and Belgium during a period known as the Oligocene. They became most diverse during the Miocene but started to disappear during the early Pliocene. Interestingly, in Australia, some of these birds managed to survive until the Pleistocene.

Today, scientists recognize three groups within this family: Adelalopus, Palaelodus, and Megapaloelodus. Most of the fossils found come from Europe and are usually identified as Palaelodus ambiguus. Because many of the fossils are incomplete, we do not know much about how these birds lived. However, it seems they liked areas with brackish water, such as lakes and lagoons. While it was once thought that Palaelodus walked or dived for food, newer studies show they were probably better at swimming and may have eaten insect larvae and other small water creatures. At least one type, Megapaloelodus, had special features that helped it stand still in one place.

History of discovery

The first fossils of these ancient birds were found in the middle of the 19th century near Saint-Gérand-le-Puy in France. A French scientist named Alphonse Milne-Edwards studied these fossils and named them Palaelodus, using words from Ancient Greek meaning "ancient" and "inhabitant of marshes." He identified several species, but later scientists realized many of these were just different sizes of the same bird.

More discoveries followed. In the 1940s and 1950s, similar fossils were found in the western United States, leading to the creation of the genus Megapaloelodus by Alden H. Miller. These birds were much larger than the European ones. In the 1980s, scientists revised the European species, and in the 1990s, important skull fossils were found. Over time, many new species and genera were described, expanding our understanding of these ancient birds.

Species

Some birds called Probalearica, "Grus" miocenicus, and Pliogrus germanicus were first thought to be cranes, but later scientists found out they were actually members of the Palaelodidae family.

Palaelodids were successful birds that lived on every continent except Antarctica. They were most common during the Miocene period.

• Eurasia

The most fossils of these birds are found in Europe. The earliest fossils, from a type called Adelalopus, were found in the early Oligocene in Hoogbutsel, Belgium. Another type, Palaelodus, has been found in many places such as Saint-Gérand-le-Puy, France, and several spots in Germany like the Mainz Basin, Nördlinger Ries, and the Steinheimer Basin. Fossils of Megapaloelodus were also found in these German areas, plus in Bohemia in the Czech Republic and Romania. In Asia, there are fewer fossils, with just one species known from the Middle Miocene Ooshin Formation in Mongolia.

• America

In America, the main fossils found are from the large type Megapaloelodus, mostly along the west coast. These include fossils from Oregon's Juntura Formation and California's Barstow Formation and the Sharktooth Hill Bonebed. More inland fossils were found in the Rosebud Formation of South Dakota. These fossils are mostly from the Miocene, except for the ones from Oregon which might be a bit later. Further south, Megapaloelodus fossils were found in the Miocene to Pliocene Almejas Formation of Cedros Island in Baja California. In South America, Megapaloelodus fossils were found in Argentina's Andalhualá and Ituzaingó Formation, and some fossils that might be from Palaelodus could be from Brazil's Taubuté Basin. However, they might also belong to Palaelodus haroldocontii, which was found in Argentina's Las Flores Formation.

• Africa

Although no specific species have been named from Africa, fossils have been found in several places. Two different sizes of fossils were found in the early Oligocene Jebel Qatrani Formation of Fayum, Egypt. A possible type of Megapaloelodus was found in the early Miocene Northern Sperrgebiet of Namibia.

• Oceania

Three types of Palaelodus have been identified in Australasia. Two of these were found in the Oligocene to Miocene Etadunna and Namba Formation within the Lake Eyre Basin. The third was found in New Zealand's Bannockburn Formation, dating to the early Miocene. While most palaelodid fossils are from the Neogene period, some younger fossils were found in the Kutjitara Formation, suggesting that these birds might have survived until about 0.2 million years ago.

Description

Palaelodids looked a bit like modern flamingos, with long legs and necks. However, they were different in some ways. For example, their necks did not have a special bend like flamingos do, and some of their bones were flatter, similar to grebes. This suggests they might have been good swimmers.

We know about the skull shape from just one species, Palaelodus ambiguus, which had a straight, cone-shaped bill, unlike the curved bills of flamingos. This species also had special glands to handle salty water, showing that at least some palaelodids lived in places with brackish water.

Palaelodids were about the same size as modern flamingos. The smallest species was Palaelodus pledgei. Others, like Palaelodus kurochkini, were about the size of an American flamingo. Some larger species, such as Megapaloelodus goliath and Adelalopus, were even bigger than today’s greater flamingo.

Phylogeny

Palaelodids are closely related to modern flamingos and are part of the group Phoenicopteriformes, which also includes flamingos from the Phoenicopteridae. Together with grebes, they make up the group Mirandornithes. Scientists believe palaelodids are closely connected to flamingos and help us understand the links between these bird families. These birds looked a bit like flamingos but had legs more like grebes. The exact family tree for palaelodids is still not fully known.

Paleobiology

Paleoenvironment

Many fossils of these ancient birds were found in places that were once shallow lakes or similar watery areas. These places often had water that was a mix of fresh and salty, much like where modern flamingos live. For example, one type of these birds, called Adelalopus, lived near a lagoon in what is now Belgium. Studies show that these areas changed over time, sometimes dry and sometimes wet, which made them good homes for these birds. We even find fossils of baby birds and eggs, showing that they raised their young there too. Similar places existed in Australia, where these birds lived alongside early types of flamingos.

These birds also lived in other kinds of watery places, like swampy areas and rivers. In New Zealand, one type lived in a big lake fed by a river, and in Namibia, they lived in fresh water areas unlike the salty lakes elsewhere.

Locomotion and feeding

We don’t know much about how these birds lived because we haven’t found enough fossils. But from what we have, it seems they fed differently from modern flamingos. Instead of the special curved beak that flamingos use to filter food, these birds might have eaten small water creatures like snails and caddisflies.

There has been debate about how these birds moved. Some think they might have dived, but their long legs don’t match what we see in diving birds today. Others believe they waded through deep water, helped by their long, thin legs. Another idea is that they swam, using their webbed feet to push through the water. Each idea has its supporters, and we may need more fossils to know for sure.