Ichnology: The Science of Traces

Ichnology explores fossilized traces left by ancient organisms, revealing their behavior and environments. This article examines the origins of ichnology, the oldest discovered traces, how footprints shaped dinosaur research, trace fossil preservation, and their role in evolutionary reconstructions.

Introduction

While the fossil remains of animals tell us about their post-mortem state, tracks show us their in vivo behavior. Thus, fossil tracks are one of the main sources of information about the behavior and movement of extinct creatures.

Additionally, body fossils can move over time from the place where the organism lived. Fossil tracks, studied within ichnology, are located exactly where the organism lived. This provides a more accurate understanding of past environments and ecosystems and the adaptation of animals to their changes.

*Ichnology is the field of paleontology*

Often, no fossils remain of soft-bodied animals, and only their tracks give us information about them. Furthermore, in some sedimentary rocks, shells and other skeletal remains may disappear, leaving traces of vital activity as the only evidence of ancient life. Ichnology plays a crucial role in interpreting such evidence.

Behavioral (ethological) characteristics of organisms are the primary determinant of the morphology of trace fossils¹. The physical characteristics of organisms usually have a lesser impact on most traces. Therefore, identifying the specific creator of a trace is often difficult. When identification is possible, the trace and the creature often receive different names. For instance, the shrimp Callianassa creates burrows known as Ophiomorpha.

Vertebrate and invertebrate ichnology differ due to track-maker morphology and behavior. Invertebrate ichnology emphasizes behavior and organism-substrate interactions, while vertebrate ichnology prioritizes foot morphology and track-trackmaker relationships. This distinction leads to ethoichnofacies for invertebrates and biotaxoichnofacies for vertebrates.

Traces allow us to learn how animals moved—crawled, walked, ran, swam, whether they moved in herds, and how predators and prey interacted. Accumulations of tracks indicate specific ichnofacies, which form under similar paleoenvironmental conditions. This gives an idea of the paleoecological setting—humidity, depths of water bodies, subaqueous substrates, lake and river margins, etc.

*A scientist places her hand alongside a fossilized dinosaur track, an example of a trace fossil. ©piola666*

Ichnological studies not only provide valuable information about the paleobiology of trace makers but also contribute to the reconstruction of entire paleocommunities.

The Beginning of Ichnology

For centuries, people have discovered fossilized tracks, often attributing them to mythical creatures or familiar animals like elephants. However, scientific understanding of these footprints only emerged in the early 19th century. The first scientifically identified trace fossils were dinosaur footprints.

A common but mistaken story claims that an English farmer found dinosaur tracks in his field in 1834. In reality, the first recorded discovery happened much earlier.

The first recognized dinosaur footprints — *“The Moody Footmark Quarry, South Hadley,” plate I from “Ichnology of New England.” Image courtesy of Pocumtuck Valley Memorial Association Library.*

Noah's Raven — *A sandstone slab with a series of footprints from Anomeopus minor and another from Ancyropus heteroclitus. Beneski Museum of Natural History at Amherst College, photograph by Penny Leveritt.*

In 1801 or 1802, a 12-year-old farm boy named Pliny Moody uncovered a slab with five bird-like, three-toed fossil footprints while plowing his father’s field in South Hadley, Massachusetts. Initially, someone used the slab as a doorstep before Dr. Elihu Dwight acquired it in 1810. Edward Hitchcock of Amherst College purchased it nearly 30 years later. This fossil, which we now attribute to the Newark Supergroup, was one of the earliest track specimens preserved. Moody called them the tracks of “Noah’s Raven,” but scientists later determined they belonged to a small ornithopod dinosaur, now classified as ichnospecies Anomoepus scambus.

“Bird tracks” found by Marsh — Dexter Marsh noticed «bird tracks» on these slabs. The left slab holds the mold, meaning the original footprints. The slab on the right has the cast, meaning the material that filled in the original tracks once they had dried enough to hold their form. Amherst College eventually purchased these plates. They are now on display at the campus’s Beneski Museum of Natural History. © Penny Leveritt

In 1835, laborer Dexter Marsh noticed similar “bird tracks” on slabs of stone used for paving a sidewalk in Greenfield, Massachusetts. He recognized a distinct pattern in the footprints, resembling bird tracks he often saw around him. Marsh wrote to “The American Journal of Science,” and they published his observations in 1848.

Dinosaur footprints from the book “Ichnology of New England” — Lithograph of a slab with dinosaur footprints. From the book “Ichnology of New England. A Report on the Sandstone of the Connecticut Valley, especially its Fossil Footmarks.” Boston: William White, 1858. The book describes a collection of fossil footprints gathered in the Connecticut River Valley by the state geologist of Massachusetts, Edward Hitchcock.

The first scientist to formally study fossil tracks was American geologist Edward Hitchcock in the 1830s and 1840s. While excavating in the Connecticut River Valley, he discovered tracks belonging to the ichnogenus Eubrontes (originally called Ornithichnites). Hitchcock initially considered them to be the tracks of giant birds, though some unusual tail marks puzzled him. He speculated that large, bird-like creatures with long, reptilian tails had left these tracks—unknowingly describing dinosaurs.

His wife, Orra White Hitchcock, illustrated these tracks for his first paper on fossil footprints, which he published in 1836. Over time, he collected nearly 2,000 tracks. Later research confirmed that these prints were made not by birds, but by dinosaurs millions of years ago. Hitchcock’s work laid the foundation for ichnology, the study of ancient tracks, offering insights into the behavior and movement of prehistoric creatures.

Similarly, people initially misidentified invertebrate tracks as ancient algae imprints and named them Fucoides. However, in 1881, Swedish paleobotanist Alfred Nathorst proved that marine invertebrates, such as polychaete worms, left many of these tracks. He then reclassified them as trace fossils like Chondrites, Zoophycos, etc.

Earliest Trace Fossils

The search for our origins takes us back to the earliest signs of life. Discoveries of ancient biological imprints provide a window into the distant past, revealing how early organisms moved, behaved, and thrived on Earth.

Single-Celled Life

*Archean stromatolites on shallow platforms, fringing volcanoes. Stromatolites are mineralized microbial communities formed from cyanobacteria (blue-green algae). ©P. Sawyer*

The first signs of life came from single-celled organisms. We find some of the earliest evidence in stromatolites—layered structures in rocks dating back about 3.5 billion years. The activity of photosynthetic microorganisms, such as cyanobacteria, resulted in these formations, as they formed thin mats interwoven with fine calcite silt. Stromatolites were widespread from the Precambrian to the Ordovician; we can still find them today.

Invertebrates

Numerous discoveries claim to be the oldest traces of life, dating back more than 1 billion years. However, many of them are most likely microbial structures or the result of the activity of single-celled organisms.

The trace fossil Myxomitodes, meaning “slime thread-like” in Greek, represents some of the earliest clear evidence of invertebrate activity, dating back 1.9 billion years. Found in Western Australia’s Stirling Range Formation, these markings resemble animal tracks but are puzzling due to their age. Unlike typical worm or slug trails, Myxomitodes stirlingensis forms short, branching impressions that vary in width, with one end tapered and the other bulbous.

Originally attributed to soft-bodied worms, later interpretations suggests giant spherical sea amoebae as the potential creators. The presence of ancient soils alongside these fossils raises the intriguing possibility that Myxomitodes occasionally lived on land, forming slug-like multicellular aggregates. However, these fossils predate the oldest known amoebozoans, leaving their true origins a mystery. The ichnology of these ancient traces is particularly challenging due to the difficulty in definitively linking them to specific organisms.

Ichnology confirms the oldest traces of multicellular organisms — *Locomotion trace from Mistaken Point Formation, Newfoundland. This is the largest trail visible on the bedding plane. Scale bars = 1 cm. ©Liu et al.*

The earliest potential traces of multicellular animals come from the 565-million-year-old deposits of the Mistaken Point Formation (Newfoundland). That location contains approximately 90 individual impressions, appearing as shallow grooves up to 13 mm wide and several centimeters long. The inner surface is smooth, but some grooves contain semicircular sediment ridges and a round pit at one end.

Precambrian trace fossils — *Precambrian bilobed trace fossils: (A) Aulichnites; (B) Archaeonassa. ©Matz*

Before the Cambrian, traces were very rare and small. Before the Cambrian, traces were very rare and small. Crawling worms, such as Aulichnites, Nereites, Bilinichnus, and Archaeonassa, likely formed them.

Invertebrates left many types of traces, including body and appendage imprints. One distinctive type of fossil trace left by invertebrates is bioerosion, which has been known since the early Cambrian and became widespread from the Ordovician onward.

Traces of Trichophycus mark the boundary between the Ediacaran and Cambrian periods in ichnology — Early Cambrian trace fossils. Trichophycus pedum (or Treptichnus), ранее Phycodes pedum, from the Lower Cambrian Mickwitzia Sandstone, Sweden (Swedish Geological Survey, Uppsala). The trace is the earliest widely distributed complex fossil. Paleontologists use its earliest appearance to define the boundary between the Ediacaran and Cambrian periods. Scale bar = 1 cm. © University Lyon. Photo: Jean Vannier.

The lower boundary of the Cambrian (541 million years ago) is marked by the horizontal trace fossil of the burrow Trichophycus pedum at the reference section in Fortune Head, southeastern Newfoundland.

The earliest terrestrial traces — *Plates with images of the tracks of Protichnites, accompanying Owen’s work (1852). Initially, they were thought to be turtle tracks, and later considered belonging to crustaceans.*

The earliest evidence of terrestrial animal activity comes from Protichnites tracks dating to the Late Cambrian. These traces were made by numerous multi-legged animals about 50 cm in size and were preserved in eolian sandstone from the Nepean (or Keeseville) Formation, Potsdam Group, near Kingston, Ontario, Canada. They were created on land in littoral and supralittoral environments. The trackmakers were likely arthropods—possibly euthycarcinoids—that ventured onto land for limited periods, rather than being fully terrestrial animals.

Early Tetrapods

The early tetrapod tracks are known from the Devonian period, found at Genoa River, Australia; Valentia Island, Ireland; and Tarbat Ness, Scotland. However, the oldest tracks come from the early Middle Devonian site in Zachełmie, Poland, dating to approximately 390 million years ago.

*Ichniotherium willsi from the Late Carboniferous Salop Formation (Alveley locality, Birmingham, UK). Scale bars equal 5 cm. ©Buchwitz and Voigt*

The oldest known traces of diadectomorphs, named Ichniotherium willsi, are approximately 315-307 million years old. These traces are from the Salop Formation, found in a quarry in Alveley, near Birmingham, Great Britain (Late Carboniferous: Late Moscovian–Kasimovian). Researchers have found similarly aged tracks in Germany.

Synapsids

Dimetropus tracks belong to basal synapsids—pelycosaurs (non-therapsid synapsids). Dimetropus salopensis from the Salop Formation is the oldest known occurrence of the ichnogenus Dimetropus.

Dicynodontipus. Dicynodont trackway. — *Dicynodontipus. Dicynodont trackway from Asante Sana, Graaff-Reinet, South Africa. ©WJ de Klerk*

The oldest dicynodont tracks, named Dicynodontipus icelsi, were discovered in Asante Sana, Graaff-Reinet, within the Cistecephalus assemblage zone of the Karoo, South Africa. While the name implies dicynodonts, cynodonts were most likely the trackmakers (Marchetti et al.). These well-preserved heteropodous footprints display clear impressions of footpads, individual toes, and claws from six large tetrapods. The tracks are believed to have been made by Aulacephalodon and date to the Late Permian–Early Triassic, approximately 253 million years ago. Similarly aged ancient dicynodont tracks have also been found in the Fremouw Formation of Antarctica and the Sydney Basin in Australia, likely belonging to Lystrosaurus.

Dinosaurs

Dinosauromorphs tracks — Comparison of the footprints of Parachirotherium postchirotherioides from the Estherienschichten horizon near Barbaraberg. The holotype (official reference specimen) consists of a five-toed (pentadactyl) footprint of both the foot and hand (labeled A). Interestingly, variations in the footprints (B-C) show differences depending on the surface where the tracks were made, sometimes appearing with three toes (tridactyl) instead of five. (Haubold & Klein, 2000).

Dinosauromorphs left their first tridactyl (three-toed) tracks in the Middle Triassic (Ladinian) Benker Sandstein of Germany. These include Parachirotherium, Atreipus, and Grallator.

The oldest known dinosaur tracks date to the Late Triassic, around 230 million years ago, and have been found in South Africa, Argentina, Australia, North America, Germany, Switzerland, and the United Kingdom. These tracks include Grallator, Atreipus, Eosauropus, Evazoum, and others, depending on the specific species.

Evazoum is a footprint of a Triassic dinosaur. — A dinosaur that lived in Australia 220 million years ago left behind footprints called Evazoum. It was a herbivorous prosauropod. So far, this is the only evidence of Triassic dinosaurs in Australia. ©Romilio, Porembinski

Some of the earliest dinosaur footprints. — Photos of replicas of Evazoum from the Upper Triassic Wolfville Formation, Nova Scotia. Note that all specimens have an enlarged proximal pad on digit II. A is a functionally didactyl, tridactyl specimen with distal claw trace on digit II. B is a functionally didactyl, tridactyl, or tetradactyl specimen with distal claw trace on digit II. © Lockley, Lucas.

The oldest well-defined dinosaur tracks are noted in Greenland. The Late Triassic (Norian–early Rhaetian, 220–208 million years old) Fleming Fjord Formation in central East Greenland has preserved a diverse fossil fauna, including fossilized tracks of large quadrupedal archosaurs. Two tracks can be attributed to Eosauropus, while a third, bipedal track is attributed to Evazoum. Both sets of tracks belong to sauropodomorph dinosaurs.

The oldest tracks of sauropodomorphs known in ichnology — Eosauropus sp. Trackway S1, here attributed to a sauropod trackmaker based on pedal synapomorphies. Trackmaker is moving towards the southwest. Two consecutive pes impressions of a tridactyl Grallator trackway can be seen left to the S1 trackway. ©Lallensack et al.

Eosauropus trackways — *Photographs showing the trackways of Eosauropus in the field. ©Lallensack et al.*

Eosauropus. Tracks show a four-toed stance, an entaxonic structure of the toe bones, and five weight-bearing toes. These characteristics indicate sauropodomorphs. Other features, including a semi-digitigrade foot and laterally deflected unguals, suggest Sauropoda. This track indicates an early acquisition of the foot anatomy characteristic of eusauropods while retaining a well-developed claw on the IV toe, which is already reduced in eusauropods. Although definitive evidence of sauropod dinosaurs exists only from the Early Jurassic, this track submits a Triassic origin for this group. (Lallensack et al., 2017)

In the UK, the oldest dinosaur footprints come from the Late Triassic (Norian) in South Wales. In the UK, the oldest dinosaur footprints come from the Late Triassic (Norian) in South Wales. Researchers discovered these footprints at a site called The Bendricks in the Vale of Glamorgan. The footprints date back to around 220 million years ago and include tracks from small theropods like Anchisauripus and Grallator, as well as sauropodomorphs like Tetrasauripus.

Birds

Late Triassic bird-like tracks — Photographs and interpretive outlines of distinct traces associated with Trisauropodiscus at Maphutseng. Some markings resembling either pecking and probing activity or partial track (digit) impressions. Morphotype II, comprising T. aviforma, T. phasianiforma, and T. superavipes, is wider than long with slender digits and a larger total digit divarication. Abbreviations: cr–crescent ring-like trace, f–figure of eight-like trace, t–teardrop-like trace. ©Abrahams et al.

Unknown animals left the first bird-like tracks as early as the Late Triassic in Lesotho (at the Maphutseng site) in Southern Africa. Their age is 210 million years, which is 60 million years older than the oldest known birds (Late Jurassic, 150–160 million years). These tracks were attributed to the ichnogenus Trisauropodiscus, which is believed to have been an ornithischian dinosaur that lived in the Late Triassic. Trisauropodiscus tracks have two distinct morphologies. One is considered synonymous with Anomoepus, belonging to ornithischian dinosaurs. The second track, with its bird-like morphology, resembles Gruipeda, a track type belonging to Charadriiformes birds. (Abrahams, Bordy, 2023)

*Fossil bird tracks in Cretaceous sandstone. UCM*

Ignotornis, bird track. — A – Photograph and B – line drawing of the Ignotornis mcconnelli holotype. Ignotornis, the first bird track morphotype formally named, and the first ever reported from the Mesozoic. It occurs in Cretaceous deposits in the Dakota Group near Golden, Colorado (after Mehl and Lockley et al.). The relatively long, reversed hallux and the incipient semi-palmate webbing in the hypex between digits III and IV make Ignotornis distinct from any other Cretaceous bird tracks known from North America. CU Denver Dinosaur Tracks Museum collections.

Avian dinosaurs (birds) appeared in the Late Jurassic period. The oldest known unambiguous bird tracks currently date to the basal part of the Early Cretaceous, 130–125 million years ago.

Mammals

Mesozoic mammal tracks — *Photographs of the type series of Ameghinichnus patagonicus. ©Silvina de Valais*

One of the first trace evidences of the existence of Mesozoic mammals is the ichnogenus Ameghinichnus. It is represented by two ichnospecies: Ameghinichnus mirabilis from the Upper Triassic-Lower Jurassic Karoo basin of South Africa and Ameghinichnus patagonicus from the Middle Jurassic of Patagonia (La Matilde Formation, Santa Cruz Province, Argentina). These five-toed footprints lack claw marks and have no pronounced phalangeal pads.

Brasilichnium—footprints of Mammaliamorphs (crown-group Mammalia). Their gait was still semi-erect. They date from the Jurassic and Cretaceous periods in the largest paleodesert of Brazil (Paraná Basin, Early Cretaceous) and in western North America (Lower Jurassic). Later, they were found in many places around the world and even in the Early Triassic Holy Cross Mountains, Poland.

Humans

Ichnology studies the earliest hominin footprints from Laetoli. — The southern part of a 70-meter-long hominin trackway lies within test pit L8 in Laetoli, Tanzania. Preserved in volcanic ash, the trackway dates back 3.6 million years. It shows that hominids walked upright and bipedally, with a gait similar to modern humans. A clear heel drag mark is visible on the trackway, which scientists attribute to Australopithecus afarensis. Mary Leakey’s expedition discovered it in 1978.

And the oldest human tracks are footprints in volcanic ash from Laetoli (Tanzania), left, presumably, by Australopithecus afarensis 3.7 million years ago.

The oldest footprints of Homo sapiens — The oldest known footprints of Homo sapiens found in South Africa. The footprint is outlined in chalk. It is 153,000 years old. It appears unusually long and narrow because it includes a heel drag. ©Charles Helm

By far the oldest footprints belonging to our species, Homo sapiens, are those found on the Cape South coast, tens of miles inland from the ancient coast. They are about 153,000 years old.

How Footprints Helped Understand Dinosaur Behavior

There are many examples of how ichnology and the study of tracks have helped to better understand the behavior of extinct dinosaurs and other animals.

Trail of the giant Hibbertopterus scorpion — Fossilized trail of the giant Hibbertopterus scorpion, who lived 300 million years ago. The trackway, which is preserved in sandstone, consists of three rows of crescent-shaped footprints on each side of a central groove. © Central Scotland News. Artistic image of eurypterid: ©Mikhail Sidorenko.

The track of the eurypterid Hibbertopterus on a sandy beach in Scotland from the Carboniferous period (330 million years ago) showed that giant sea scorpions could exist out of the water for some time. It would have been impossible to obtain such knowledge from body remains alone.

Pterodactyloid trackway — Unusual pterodactyloid trackway (Early Tithonian, Crayssac, France), showing landing behavior. (a) Photograph of the trackway, with manus and pes prints indicated by white arrows. The trackways are so shallow that even in strongly oblique light (note the shadow of the scale bar), their outlines and features are difficult to photograph. (b) Drawing of the trackway. Scale bar = 5 cm. RP, right pes print; LP, left pes print; RM, right manus print; LM, left manus print. ©Mazin et al.

In the case of pterosaurs (flying reptiles), tracks from the Late Jurassic Crayssac, France, demonstrated how they moved on land or landed after flight. (Mazin et al., 2009)

Most dinosaur tracks indicate a leisurely pace of 2 to 12 km/h. However, several bipedal tracks (including a unique track found in Australia in the 1970s) indicate speeds of over 40 km/h.

In the Gobi Desert in Mongolia and in North America (Utah and Texas), paleontologists have discovered tracks that suggest dinosaurs may have lived in herds.

In North America, researchers discovered long chains of sauropod tracks going in one direction with a certain hierarchy: young individuals walked in the center for protection from predators, and adults on the edges.

Tracks of juveniles next to adult dinosaur tracks provide a unique opportunity to compare the sizes and features of dinosaur locomotion at different ages and draw conclusions about their development.

Traces of dinosaur hunting behavior — «Chase sequence», in which a carnivorous theropod (bipedal trackway, left), possibly Acrocanthosaurus, was thought to be following an herbivorous sauropod (quadrupedal trackway, right). Both trackways bend to the left over their course, and the theropod repeatedly stepped in and deformed the prints of the sauropod. This scene is based on fossil tracks found at Glen Rose, Texas, USA, dating from the Late Jurassic. The fossil tracks were discovered by Roland T. Bird in 1938. ©American Museum of Natural History

In the 115–110 million-year-old Glen Rose Formation in Texas (USA), theropod tracks run parallel to sauropod tracks. This arrangement may indicate hunting behavior, with predators pursuing herbivores.

The biggest dinosaur footprint — The biggest sauropod prints are over a meter long. This footprint is Broome sauropod morphotype A, from the Yanijarri–Lurujarri section of the Dampier Peninsula, Western Australia. Lower Cretaceous (Valanginian–Barremian). ©Salisbury et al.

The largest dinosaur footprint, 130 million years old (Early Cretaceous) and 1.7 m in size, was discovered on the Kimberley coastline, on the northwest coast of Western Australia. This footprint, designated “Broome sauropod morphotype A,” reveals the immense size that these animals could reach. The height of this sauropod at the hip reached 5.3 to 5.5 m.

Prior to this discovery, the largest dinosaur footprints were considered to be the footprints of a bipedal hadrosaurid (duckbill)—1.36 m long and 81 cm wide, Salt Lake City, Utah, USA, and sauropod tracks from the UK (Keates Quarry, Worth Matravers, Dorset)—140 million years old, slightly exceeding 1 m in diameter.

Supplementary Aspects of Ichnology

This section explores additional aspects of ichnology, such as the preservation of trace fossils, evolutionary reconstruction, and the variability of ichnological evidence.

Preservation of Trace Fossils

Ichnotaphonomy is the study of how trace fossils preserve. The specific environmental conditions during formation determine the preservation of fossil tracks. Then, the environment, through the sedimentation processes, plays a role that enhances the origin and quality of the tracks and their preservation.

Sediment Type

Ichnological studies take into account sediment consistency. — Track variations related to sediment consistency. All the tracks shown were made by a single dinosaur stepping on substrates of different consistencies, with the firmer substrates on the left and the softer ones on the right. Notice the absence of distinct pads in the deeper prints (at right). The rightmost track suffers from “mud collapse” or “mud back-flow,” where soft sediment slumps back into a track depression, distorting its shape. Adapted from Thulborn (1990).

Tracks remain on soft ground, such as on the shores of seas, lakes, and rivers. For clear, detailed tracks, the soil should not be too hard or too soft. If the substrate is too hard, the track will be shallow, not detailed, or may not form at all. Too soft soil can lead to the destruction of the imprint. Sedimentary rocks that are quickly buried and protected from erosion are more likely to preserve fossil tracks. Fine-grained deposits preserve delicate fossil tracks better than coarse-grained sediments. Additionally, certain types of sediment, such as volcanic ash, can create exceptional preservation conditions due to their rapid deposition and fine particle size. These factors are all crucial considerations within ichnology.

Taphonomy

After the death of an organism, decomposition and fossilization processes take place in the organism. Different environmental factors, such as pH levels, temperature, and the presence of scavengers or decomposers, can significantly impact the preservation of footprints.

Diagenesis

This refers to the physical and chemical changes that occur in sediments after they are deposited. Diagenetic processes, such as compaction and cementation, can alter the original footprint and affect its preservation.

Erosional Forces

Wind, water, and other erosional forces can degrade or erase footprints over time. Rapid burial by sediments can protect footprints from erosion and enhance their preservation.

Evolutionary Reconstruction

Fossil tracks can also provide insight into the evolution of ancient organisms. For example, the discovery of early tetrapod tracks provided evidence that these animals began walking on land much earlier than previously thought. They also show how the limbs evolved and adapted to walking on land.

Similarly, trace fossils of ancient invertebrates can provide information about the evolution of their feeding and locomotion habits.

The following additional considerations are relevant for evolutionary reconstruction based on fossilized prints:

Anatomical Changes: Fossilized footprints can reveal how the anatomy of ancient organisms changed over time. For example, changes in the structure of feet, toes, or claws can indicate evolutionary adaptations to different environments or lifestyles.

Locomotion Efficiency: By studying the spacing, depth, and pattern of footprints, scientists can infer the efficiency of an organism’s locomotion. This can help identify evolutionary trends toward more efficient movement, such as changes from sprawling to more upright postures.

Ontogenetic Changes: Fossilized footprints can show how the locomotion and behavior of an organism changed as it grew. Differences between juvenile and adult footprints can provide insights into the life history and developmental stages of ancient species.

Comparative Analysis: By comparing footprints from different geological periods, scientists can track evolutionary changes over time. This can reveal patterns of diversification, extinction, and adaptation across various groups of organisms.

Ichnological Variability

Trace fossils can vary significantly in their morphology and preservation, making it challenging to compare different specimens. Ichnological variability refers to the natural variation in the morphology and preservation of trace fossils. Ichnological variability refers to the natural variation in the morphology and preservation of trace fossils. For example, a dinosaur trackway from one location may look very different from a dinosaur trackway from another location, even if the same species of dinosaur made them.

The three-toed footprints attributed to Dilophosaurus exemplify the challenges in trace fossil identification. Different researchers at different times have assigned them to a wide range of ichnogenera, such as Dilophosauripus, Eubrontes, Grallator, Kayentapus, Gigandipus, and Anchisauripus.

Local changes in environmental conditions, changes in the composition and consistency of deposits, differences between individuals due to age, sex, health, or even random variations, or changes in the behavior of organisms can lead to the appearance of different tracks.

Conversely, similar behavior between taxonomically unrelated organisms can create very similar tracks. For example, Chondrites.

* * *

By studying these diverse types of trace fossils, paleontologists can reconstruct ancient ecosystems, understand the interactions between organisms, and gain a deeper appreciation for the complexity of life in the past. Ichnology plays an important role in interpreting such evidence.

Thus, the study of dinosaur tracks provides valuable information that complements the data obtained from the study of bones.

William A. S. Sarjeant, 1987. The Study of Fossil Vertebrate: Footprints A Short History and Selective Bibliography. ↩︎