Bird ichnology

Last updated
Male common teal producing feeding traces on a River Tyne mudflat. Anas crecca m.jpg
Male common teal producing feeding traces on a River Tyne mudflat.

Bird ichnology is the study of avian life traces in ornithology and paleontology. Such life traces can include footprints, nests, feces and coproliths. Scientists gain insight about the behavior and diversity of birds by studying such evidence.

Contents

Ichnofossils (or ichnites) are especially important for clarifying the evolution and prehistoric diversity of taxa. These cannot usually be associated with a particular genus, let alone species of bird, as hardly ever they are associated with fossil bones. But it is possible to group them into ichnotaxa based on their morphology (form). In practice, the details of shape that reveal the birds' behavior or biologic affinity are generally given more weight in ichnologic classification.

Bird ichnofossils

Bird footprints typically have a wider angle between the toes. These goose tracks show that webs do not necessarily leave an impression. Goosed.jpg
Bird footprints typically have a wider angle between the toes. These goose tracks show that webs do not necessarily leave an impression.
Grallator are the footprints of a Coelophysis-like theropod, initially mistaken for those of a ratite bird. Grallatorgrs.jpg
Grallator are the footprints of a Coelophysis -like theropod, initially mistaken for those of a ratite bird.
Footprints of a large moa found in 1911 Moa footprints.jpg
Footprints of a large moa found in 1911

These fossil traces of birds are sometimes hard to interpret correctly, especially when they are from the Mesozoic when the birds' dinosaurian relatives were still in existence. Nests at least of Neornithes are usually quite easy to identify as such due to the unique structures of their eggshells; there is some uncertainty as regards the origin of certain Mesozoic eggshells, which makes nests of this age problematic.

Mesozoic fossil footprints are hardest to attribute. "Proto-bird" and related theropod feet were very much alike; non-avian theropod tracks such as the ichnogenus Grallator were initially attributed to ratites because in the early 19th century when these were described, the knowledge about dinosaurian diversity was marginal compared to today, whereas ratites were well-known. Also, under the creationist dogma, scientists would believe that e.g. rheas had been around for all eternity. In the Jurassic and Early Cretaceous, juvenile non-avian theropods left very birdlike footprints. Towards the end of the Cretaceous, the tracks of aquatic birds are usually recognizable due to the presence of webbing between the toes; indeed, most avian ichnotaxa fall into this group. However, giant flightless birds also existed by that time, as evidenced by Gargantuavis ; if the Gastornithidae were indeed close to Anseriformes, their lineage must also have been distinct by then. Such footprints may resemble those of non-avian theropod or even ornithopod dinosaurs. Among the former, the Ornithomimiformes (= "Arctometatarsalia" sensu stricto) were convergent to ratites in many respects, including the feet, and it is impossible to tell if some large bird-like footprints from the Late Cretaceous are from an ornithomimiform or a giant bird, without associated bone material. [1]

Footprints

48-million-year-old bird and mammal footprints from the Early Eocene Green River Formation Track of Footprints of Many Mammals and Birds.jpg
48-million-year-old bird and mammal footprints from the Early Eocene Green River Formation

There exist documented tracks that appear avian since the Late Triassic, by some 55 million years predating the first proper evidence that very birdlike theropods were present. The Late Triassic and early-mid Jurassic tracks have been assigned to the ichnogenera Trisauropodiscus and Aquatilavipes. Few scientists would go as far though to consider these traces evidence that birds evolved much earlier than generally believed, and perhaps not from theropod dinosaurs as per today's mainstream opinion. In fact, it seems that the initial dating of these very ancient bird-like tracks was in error, and they seem to date from a much later time when modern birds were already known from bone fossils.

Footprints of at least Neornithes can be distinguished by several features:

It is notable that Heterodontosauridae are known from the localities and times when the first avian-looking footprints started to appear. These small ornithopod dinosaurs were entirely unbirdlike, except for their ornithischian pelvis and a tarsometatarsus strongly convergent to that of Enantiornithes. Though some details remain unresolved, it is far more plausible that Trisauropodiscus etc. were made by a Heterodontosaurus -like animal rather than some sort of bird.

Avian? Non-avian theropod (juvenile Grallator )? Heterodontosaurid?
No hallux; Avian?
5–6 × 4–5 cm (h/v). Toes long, narrow, small webs; no or very small hallux; T2-T4 100–140°; toe pads; step 20 cm. Avian: Patagopteryx? shorebird?
35 × 35 cm (h/v). Toes long, wide; no hallux; T2-T4 110°; toe pads; step 208cm. Avian: giant flightless bird?
4-4.5 × 3-3.5 cm (h/v w/o hallux). Toes long, thin, T3-T4 small webs, T2 shorter; hallux backwards and high; T1-T4 220°; T2-T4 140–150°. Avian: shorebird
6.5–7.5 × 5–6 cm (h/v w/o hallux). Toes long, thin, unwebbed, T2 shorter; hallux backwards, high; T1-T4 225°; T2-T4 95–160°; toe pads. Avian: shorebird
2.5–3.5 × 2.5-3 cm (h/v w/o hallux). Toes long, thin, unwebbed; hallux backwards, high, very small; T1-T4 180; T2-T4 90–135°; toe pads. Avian: shorebird
2.3 × 3.5 cm (h/v). Toes narrow, unwebbed, T2+T4 shorter; no hallux; T2-T4 75–80°. Avian? perching bird?
25 × 20 cm (h/v). Toes long, very thin; no hallux; T2-T4 109–118°; step 200-217cm. Avian?
3.3–5.1 × 3.3–4.7 cm (h/v w/o hallux). Toes long, narrow, unwebbed; hallux small, high, backwards and inwards; T1-T4 270–320°, T2-T4 88–141°; step c.15 cm. Avian: shorebird?
6 × 9 cm (h/v). Toes long, thin, unwebbed; hallux backwards, some zygodactyl; T1-T4 220°; T2-T4 135°; toe pads. Avian: cursorial bird
c.4 × 3.7 cm (h/v). Toes long, narrow, fully webbed; no hallux; T2-4 c.100°. Avian: waterbird
3.5 × 3 cm (h/v). Toes narrow, unwebbed, T2 separated (higher); no hallux; T2-T4 100–120°; step 20 cm. Avian?
c.9 × 9 cm (h/v). Toes long, thin; hallux backwards; T1-T4 c.215°; T2-T4 c.150°; Toes webbed, no distinct toe pads. Avian: shorebird
30 × 25–30 cm (h/v). Toes long, thin; hallux sideways; T1-T4 130–170°; T2-T4 90°; deep heel; toe pads. Avian?
No hallux. Avian: enantiornithine? neornithine (galliform)?
Avian: shorebird?
Web impressions present; Avian: presbyornithine?
Web impressions may be present; Avian: anseriform? charadriiform?
c.10 × 9 cm (h/v). Toes long, thin, may be partially webbed; hallux small, backwards; T1-T4 190°; T2-T4 130°. Avian: large stork-like wading bird or basal waterfowl. [2]
c.27 × 32 cm (h/v). Toes long, wide; no hallux; T2-T4 65°; deep heel; toe pads. May be from Gastornis ; validity disputed. [4]
Avian: shorebird?
Web impressions sometimes present; Avian: waterbirds (Anseriformes, Charadriiformes, Ciconiiformes, Rallidae?)
Web impressions present; Avian
Web impressions present; Avian: anseriform?

Ichnofamily Ignotornidae

6 × 5 cm (h/v w/o hallux). Toes long, narrow, unwebbed or partial small webs, T2 smaller; hallux backwards and high; T1-T4 220°, T2-T4 130–145°; toe pads; step 33 cm. Avian: Neuquenornis? shorebird?
x. 7 × 6 cm (h/v w/o hallux). Toes long, narrow, T2+3 partially, T3+4 fully webbed; hallux large; 1–4 c.225°; T2-4 c.110°. Avian: shorebird

Egg fossils (ootaxa)

Fossil eggshells are not actually ichnofossils. As they preserve direct evidence of an organism's physiology, their shape, size and the structure of the eggshell give more robust clues to their origin than do footprints. Typically, fossil eggs can be quite unequivocally assigned to a specific group of organisms, e.g. chelonians, squamates, dinosaurs, crocodiles, pterosaurs or (modern) birds.

Still, egg fossils rarely are identifiable even to family, let alone to species. Thus, they are assigned to ootaxa, which are much like ichnotaxa but form a distinct group (Veterovata) in parataxonomy. For the time being however, ootaxa assigned to prehistoric birds at least tentatively are listed here:

See also

Related Research Articles

<span class="mw-page-title-main">Charadriiformes</span> Order of birds

Charadriiformes is a diverse order of small to medium-large birds. It includes about 390 species and has members in all parts of the world. Most charadriiform birds live near water and eat invertebrates or other small animals; however, some are pelagic (seabirds), others frequent deserts, and a few are found in dense forest. Members of this group can also collectively be referred to as shorebirds.

<span class="mw-page-title-main">Theropoda</span> Clade of dinosaurs

Theropoda, whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally carnivorous, although a number of theropod groups evolved to become herbivores and omnivores. Theropods first appeared during the Carnian age of the late Triassic period 231.4 million years ago (Ma) and included the majority of large terrestrial carnivores from the Early Jurassic until at least the close of the Cretaceous, about 66 Ma. In the Jurassic, birds evolved from small specialized coelurosaurian theropods, and are today represented by about 10,500 living species.

<span class="mw-page-title-main">Palaeognathae</span> Infraclass of birds

Palaeognathae is an infraclass of birds, called paleognaths or palaeognaths, within the class Aves of the clade Archosauria. It is one of the two extant infraclasses of birds, the other being Neognathae, both of which form Neornithes. Palaeognathae contains five extant branches of flightless lineages, termed ratites, and one flying lineage, the Neotropic tinamous. There are 47 species of tinamous, five of kiwis (Apteryx), three of cassowaries (Casuarius), one of emus (Dromaius), two of rheas (Rhea) and two of ostriches (Struthio). Recent research has indicated that paleognaths are monophyletic but the traditional taxonomic split between flightless and flighted forms is incorrect; tinamous are within the ratite radiation, meaning flightlessness arose independently multiple times via parallel evolution.

<span class="mw-page-title-main">Evolution of birds</span> Derivation of birds from a dinosaur precursor

The evolution of birds began in the Jurassic Period, with the earliest birds derived from a clade of theropod dinosaurs named Paraves. Birds are categorized as a biological class, Aves. For more than a century, the small theropod dinosaur Archaeopteryx lithographica from the Late Jurassic period was considered to have been the earliest bird. Modern phylogenies place birds in the dinosaur clade Theropoda. According to the current consensus, Aves and a sister group, the order Crocodilia, together are the sole living members of an unranked reptile clade, the Archosauria. Four distinct lineages of bird survived the Cretaceous–Paleogene extinction event 66 million years ago, giving rise to ostriches and relatives (Palaeognathae), waterfowl (Anseriformes), ground-living fowl (Galliformes), and "modern birds" (Neoaves).

<i>Jeholornis</i> Extinct genus of birds

Jeholornis is a genus of avialans that lived between approximately 122 and 120 million years ago during the early Cretaceous Period in China. Fossil Jeholornis were first discovered in the Jiufotang Formation in Hebei Province, China and additional specimens have been found in the older Yixian Formation.

<i>Eubrontes</i>

Eubrontes is the name of fossilised dinosaur footprints dating from the Late Triassic and Early Jurassic. They have been identified from France, Poland, Slovakia, Czech Republic, Italy, Spain, Sweden, Australia (Queensland), US, India, China and Brazil (South).

<span class="mw-page-title-main">Alan Feduccia</span> American academic

John Alan Feduccia is a paleornithologist specializing in the origins and phylogeny of birds. He is S. K. Heninger Distinguished Professor Emeritus at the University of North Carolina. Feduccia's authored works include three major books, The Age of Birds, The Origin and Evolution of Birds, Riddle of the Feathered Dragons, and many peer-reviewed papers in ornithological and biological journals.

<span class="mw-page-title-main">Paraves</span> Clade of all dinosaurs that are more closely related to birds than to oviraptorosaurs

Paraves are a widespread group of theropod dinosaurs that originated in the Middle Jurassic period. In addition to the extinct dromaeosaurids, troodontids, anchiornithids, and possibly the scansoriopterygids, the group also contains the avialans, which include diverse extinct taxa as well as the over 10,000 species of living birds. Basal members of Paraves are well known for the possession of an enlarged claw on the second digit of the foot, which was held off the ground when walking in some species. A number of differing scientific interpretations of the relationships between paravian taxa exist. New fossil discoveries and analyses make the classification of Paraves an active subject of research.

<i>Yixianornis</i> Extinct species of bird

Yixianornis is a bird genus from the early Cretaceous period. Its remains have been found in the Jiufotang Formation at Chaoyang dated to the early Aptian age, around 120 million years ago. Only one species, Yixianornis grabaui, is known at present. The specific name, grabaui, is named after American paleontologist Amadeus William Grabau, who surveyed China in the early 20th century.

Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1998.

Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1980.

<span class="mw-page-title-main">Avisauridae</span> Extinct family of birds

Avisauridae is a family of extinct enantiornithine dinosaurs from the Cretaceous period, distinguished by several features of their ankle bones. Depending on the definition used, Avisauridae is either a broad and widespread group of advanced enantiornithines, or a small family within that group, restricted to species from the Late Cretaceous of North and South America.

Eremopezus is a prehistoric bird genus, possibly a palaeognath. It is known only from the fossil remains of a single species, the huge and presumably flightless Eremopezus eocaenus. This was found in Upper Eocene Jebel Qatrani Formation deposits around the Qasr el Sagha escarpment, north of the Birket Qarun lake near Faiyum in Egypt. The rocks its fossils occur in were deposited in the Priabonian, with the oldest dating back to about 36 million years ago (Ma) and the youngest not less than about 33 Ma.

<i>Saurexallopus</i> Dinosaur footprint

Saurexallopus is an ichnogenus of four-toed theropod footprints from the Late Cretaceous period. The type ichnospecies is S. lovei, named and described in 1996 from the Harebell Formation. The taxon was originally named Exallopus, but later renamed as Saurexallopus as the former was preoccupied by a polychaete. A second species, S.zerbsti, was named and described in 2004 from the Lance Formation. In 2012 a four-toed track from the Cantwell Formation was referred to Saurexallopus indet. It was also suggested that Saurexallopus was produced by a therizinosaur taxon. In 2013 based on skeletal proportions it was suggested that the ichnotaxon was instead produced by an oviraptorosaur taxon. In 2014 a third species was named, S.cordata, from the Wapiti Formation. In 2018 several tracks from the Blackhawk Formation were referred to Saurexallopus indet.

<span class="mw-page-title-main">20th century in ichnology</span>

The 20th century in ichnology refers to advances made between the years 1900 and 1999 in the scientific study of trace fossils, the preserved record of the behavior and physiological processes of ancient life forms, especially fossil footprints. Significant fossil trackway discoveries began almost immediately after the start of the 20th century with the 1900 discovery at Ipolytarnoc, Hungary of a wide variety of bird and mammal footprints left behind during the early Miocene. Not long after, fossil Iguanodon footprints were discovered in Sussex, England, a discovery that probably served as the inspiration for Sir Arthur Conan Doyle's The Lost World.

Incognitoolithus is an oogenus of medioolithid fossil bird egg. It is notable for bearing evidence of predation, possibly from a bird pecking the eggshell.

Plagioolithus is an oogenus of fossil egg. It is from the Early Cretaceous of Japan. It was probably laid by a bird, making it the oldest known fossil bird egg.

The year 2017 in archosaur paleontology was eventful. Archosaurs include the only living dinosaur group — birds — and the reptile crocodilians, plus all extinct dinosaurs, extinct crocodilian relatives, and pterosaurs. Archosaur palaeontology is the scientific study of those animals, especially as they existed before the Holocene Epoch began about 11,700 years ago. The year 2017 in paleontology included various significant developments regarding archosaurs.

<i>Bellatoripes</i> Trace fossil of tyrannosaurid footprints

Bellatoripes is an ichnogenus of footprint produced by a large theropod dinosaur so far known only from the Late Cretaceous of Alberta and British Columbia in Canada. The tracks are large and three-toed, and based on their size are believed to have been made by tyrannosaurids, such as Albertosaurus and Daspletosaurus. Fossils of Bellatoripes are notable for preserving trackways of multiple individual tyrannosaurids all travelling in the same direction at similar speeds, suggesting the prints may have been made by a group, or pack, of tyrannosaurids moving together. Such inferences of behaviour cannot be made with fossil bones alone, so the record of Bellatoripes tracks together is important for understanding how large predatory theropods such as tyrannosaurids may have lived.

Wakinyantanka is an ichnogenus of footprint produced by a large theropod dinosaur from the Late Cretaceous Hell Creek Formation of South Dakota. Wakinyantanka tracks are large with three long, slender toes with occasional impressions of a short hallux and narrow metatarsals. Wakinyantanka was the first dinosaur track to be discovered in the Hell Creek Formation, which remain rare in the preservational conditions of the rocks. The potential trackmakers may be a large oviraptorosaur or a small tyrannosaurid.

References

  1. Wright, Joanna L. (2004): Bird-Like Features of Dinosaur Footprints. In: Currie, Philip J.; Koppelhus, Eva B.; Shugar, Martin A. & Wright, Joanna L. (eds.): Feathered Dragons: Studies on the Transition from Dinosaurs to Birds: 167–184. Indiana University Press. ISBN   0-253-34373-9
  2. Payros, Aitor; Astibia, Humberto; Cearreta, Alejandro; Pereda-Suberbiola, Xabier; Murelaga, Xabier & Badiola, Ainara (1930). "The Upper Eocene South Pyrenean Coastal Deposits (Liedena Sandstone, Navarre): Sedimentary Facies, Benthic Foraminifera and Avian Ichnology". Facies. 42 (1): 19–23. doi:10.1007/BF02562569.
  3. Similar footprints, now lost, were reported from roughly contemporary strata in France in the 19th century: Buffetaut, Eric (2004). "Footprints of Giant Birds from the Upper Eocene of the Paris Basin: An Ichnological Enigma". Ichnos. 11 (3–4): 357. doi:10.1080/10420940490442287.
  4. Patterson, John & Lockley, Martin (2004). "A Probable Diatryma Track from the Eocene of Washington: An Intriguing Case of Controversy and Skepticism". Ichnos. 11 (3–4): 341. doi:10.1080/10420940490442278.

Further reading