Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Nov 15;18(11):e0293308.
doi: 10.1371/journal.pone.0293308. eCollection 2023.

Earliest known Gondwanan bird tracks: Wonthaggi Formation (Early Cretaceous), Victoria, Australia

Anthony J Martin  1 , Melissa Lowery  2 , Michael Hall  2 , Patricia Vickers-Rich  2 , Thomas H Rich  3 , Claudia I Serrano-Brañas  4   5 , Peter Swinkels  3
Affiliations

Earliest known Gondwanan bird tracks: Wonthaggi Formation (Early Cretaceous), Victoria, Australia

Anthony J Martin et al. PLoS One. .

Abstract

The fossil record for Cretaceous birds in Australia has been limited to rare skeletal material, feathers, and two tracks, a paucity shared with other Gondwanan landmasses. Hence the recent discovery of 27 avian footprints and other traces in the Early Cretaceous (Barremian-Aptian, 128-120 Ma) Wonthaggi Formation of Victoria, Australia amends their previous rarity there, while also confirming the earliest known presence of birds in Australia and the rest of Gondwana. The avian identity of these tracks is verified by their tridactyl forms, thin digits relative to track lengths, wide divarication angles, and sharp claws; three tracks also have hallux imprints. Track forms and sizes indicate a variety of birds as tracemakers, with some among the largest reported from the Early Cretaceous. Although continuous trackways are absent, close spacing and similar alignments of tracks on some bedding planes suggest gregariousness. The occurrence of this avian trace-fossil assemblage in circumpolar fluvial-floodplain facies further implies seasonal behavior, with trackmakers likely leaving their traces on floodplain surfaces during post-thaw summers.

PubMed Disclaimer

Conflict of interest statement

No authors have competing interests.

Figures

Fig 1
Fig 1. Locality map of Wonthaggi Formation avian tracksites, Victoria, Australia.
(A)Approximate outcrop area of Wonthaggi Formation indicated (red box). Map of Australia downloaded from Mapswire (https://mapswire.com/maps/australia/), which are provided under a Creative Commons (CC-BY 4.0) license; accessed and retrieved September 21, 2023. (B) Wonthaggi Formation coastal outcrops and locations of avian tracksites for this study, with “Honey Bay” (HB) at S 38° 39.9’, E 145° 40.5’ and “Footprint Flats” (FF) at S 38° 39.4’, E 145° 41.0’; “Dinosaur Dreaming” (DD) site is at S 38° 39.5”, E 145° 41.2’. Map was drawn and adapted from public-domain satellite images at EarthExplorer (https://earthexplorer.usgs.gov).
Fig 2
Fig 2. Stratigraphic section of Wonthaggi Formation at Footprint Flats locality.
Sandstone bed numbers (FF-1 through FF-5A-B) for stratigraphic levels bearing tracks. “F” and red lines denote faults, with one fault less than a meter above FF-1 and another about 11 meters above FF-5. Colors used in this section do not match those of lithofacies.
Fig 3
Fig 3. Measurements applied to avian tracks in this study.
L = length, W = width, EL = extended length (with digit I), DL = digit length, DW = digit width, IA-I-II = interdigital angle for digits I-II (if present), IA-II-III = interdigital angle for II-III, IA-III-IV = interdigital angle for III-IV. Total divarication is the sum of interdigital angles for digits II-IV. Example track is depicted with average interdigital angles for all tracks with digits II-IV in this study (n = 25), with digits II-III = 53°, digits III-IV = 63°, and a divarication of 116°.
Fig 4
Fig 4. Polyester-resin cast duplicating tracks in rocky intertidal environment at Footprint Flats (FF) locality.
(A) Bedding planes of FF-5A (lower surface) and FF-5B (upper surface), with seven tracks (circled) photographed just before molding on November 11, 2020; ruler = 15 cm long. (B) Resin cast of bedding plane, with same seven tracks indicated; scale with centimeters. See text for key to specimen numbers, Table 1 for measurements of tracks, and S1 File for description of molding and casting methods.
Fig 5
Fig 5. Avian track in sandy siltstone from Wonthaggi Formation at Honey Bay locality.
(A) Footprint HB-1, with digits II-IV indicated. (B) Line drawing of HB-1 footprint with overlay of inferred foot morphology. Note deformation of bedding immediately behind digit III and the remainder of the track, suggesting the possible effect of a digit I (I?). Scale = 1 cm in both.
Fig 6
Fig 6. Ungual and digit impressions near a more clearly defined avian footprint in the Wonthaggi Formation, Footprint Flats.
(A) Two ungual prints next to FF-4-5 (left) and a nearby incomplete track (two digits registered), with each ungual and digit denoted by arrows; ungual print behind FF-4-5 gives misleading appearance of a digit I for that track. (B) Overlay of inferred foot morphology for FF-4-5 and estimated anisodactyl-incumbent track based on two ungual prints. (C) Overlay of inferred foot morphology for incomplete track with only partial prints of two digits. For paired ungual and digit prints, one is presumed as digit III and the other as either II or IV. Photo scale = 5 millimeter squares.
Fig 7
Fig 7. Wonthaggi Formation avian tracks with uneven depths of digit impressions.
(A, B) Photo (A) and line drawing (B) of track FF-4-3, interpreted as a right pes, with overlay of inferred foot morphology. Digits II and III penetrated to the underlying mudstone layer, but with shallow and distal impressions of digit IV. (C, D) Photo (C) and line drawing (D) of FF-4-4, interpreted as a right pes with overlay of inferred foot morphology. Digits II and IV reached the underlying mudstone layer, but digit III barely registered. Proximal interdigital webbing is inferred for both tracks, but these features also may be from foot-sediment interactions. Scale = 5 cm in all parts; see Fig 2 and Table 1 for stratigraphic position and specimen measurements, respectively.
Fig 8
Fig 8. Wonthaggi Formation avian track with digits defined by distal ends and ungual impressions.
(A) Photo and (B) line drawing of track FF-5B-1 (polyester cast), interpreted as right pes, with ungual imprint of digit IV and slight disruption of bedding (arrows) as evidence for that digit, and inferred foot morphology overlain. Scale in both = 1 cm.
Fig 9
Fig 9. Differing sedimentary expressions of digit I in Wonthaggi avian tracks.
(A, B) Photo and line drawing FF-1-3, with inferred foot morphology overlain. Because digit I is clearly defined, this track is classified as anisodactyl. (C, D) Photo and line drawing of FF-1-4. A probable digit I impression in FF-1-4 is obscured by disturbed sediment behind digits II-IV. Because of this uncertainty, the latter track was classified as anisodactyl incumbent. Scale = 5 cm in both B and D.
Fig 10
Fig 10. Anisodactyl track FF-5B-2.
(A) Outcrop view of track on November 11, 2020. (B) Polyester-resin cast of track. (C) Line drawing with overlay of inferred foot morphology. Track is interpreted as a right pes with full anisodactyl expression, sedimentary structures (ridges) in front of digits II-IV, and a thin hooked groove associated with digit I. Scale bar = 5 cm in all parts.
Fig 11
Fig 11. Anisodactyl track FF-5B-4.
(A) Outcrop view of track on May 25, 2022. (B) Line drawing with overlay of inferred foot morphology. Track is interpreted as right pes, with sedimentary structures (ridges) in front of digits II-IV and a thin linear groove associated with digit I, presumably imparted by the ungual. Scale bar = 5 cm in both parts.
Fig 12
Fig 12. Closely associated Wonthaggi tracks and single-digit impression with prominent extramorphological features.
(A) Outcrop view of FF-5A3, FF-5A-4, and single digit (SD); photo taken on November 11, 2020. (B) Polyester resin cast of tracks and single-digit impression. (C) Line drawings of FF-5A-3 and FF-5A-4 tracks, single-digit impression, and extramorphological structures, with overlays of inferred foot morphology for each track and digit. Ruler in A is in millimeters, scale bar in B and C = 5 cm.
Fig 13
Fig 13. Size-frequency distributions of lengths and widths for Wonthaggi Formation tracks with digits II-IV.
(A) Track lengths. (B) Track widths. Bins are 10 mm for each parameter (e.g., 40–49 mm), with number of tracks in each bin and mean, standard deviation, minimum, and maximum values; lengths exclude extended lengths for tracks with digit I. See Table 1 for specimen numbers and values.
Fig 14
Fig 14. Wonthaggi bird tracks affected by modern erosion and marine organisms at Footprint Flats locality.
(A) FF-3-1-1, interpreted as left pes, with widened (eroded) digits and encrusted by algae, barnacles, and gastropods. (B) FF-3-5, interpreted as right pes, with barnacles and gastropods on track center and within digits. Scale bar = 5 cm in both.
Fig 15
Fig 15. Similar orientations of closely spaced bird-track assemblages on Wonthaggi bedding planes.
(A) Bed FF-3, with azimuth orientations between 235–340° for tracks on bedding plane. Depression denoting possible track (PT) also points in northwestern quadrant at 310°; photo scale in centimeters. (B) Bed FF-5, with azimuth orientations between 230–270° for four of five tracks on lower bedding plane (5A) and identical azimuths of 165° for two tracks on upper bedding plane (5B). Ruler (left) = 15 cm long.
Fig 16
Fig 16. Invertebrate burrows and avian tracks in Wonthaggi Formation.
(A) Specimen FF-4-2 with oval cross-sections of sand-lined burrows closely associated with track (arrows); scale = 5 mm squares. (B) Close-up of burrow cross-sections on left side of track, with two sand-lined nearly intersecting on right; scale = 1 cm. (C) Specimen FF-5B-4 with circular cross-sections of unlined burrows (arrows); scale = 5 mm squares. (D) Line drawing of FF-5B-4 denoting locations of circular to semi-circular burrow cross-sections with track; scale = 5 cm.
See this image and copyright information in PMC

Similar articles

See all similar articles

References

    1. Murray PF, Vickers-Rich P. Magnificent mihirungs: The colossal flightless birds of the Australian dreamtime. Bloomington, Indiana: Indiana University Press; 2004.
    1. Mayr G. Two-phase extinction of “Southern Hemispheric” birds in the Cenozoic of Europe and the origin of the Neotropic avifauna. Palaeobiodiversity and Palaeoenvironments 2011;91: 325–333.
    1. Jetz W, Thomas G, Joy J, Hartman K, Mooers AO. The global diversity of birds in space and time. Nature 2012;491: 444–448. doi: 10.1038/nature11631 - DOI - PubMed
    1. Worthy TH, Nguyen JMT. An annotated checklist of the fossil birds of Australia. Transactions of the Royal Society of South Australia 2020;144: 66–108.
    1. Molnar RE. An enantiornithine bird from the Lower Cretaceous of Queensland, Australia. Nature 1986;322: 736–738.