Transitional Sequences

Wise, Kurt P.  “Towards a Creationist Understanding of 'Transitional Forms'.”  CEN Technical Journal (now Journal of Creation) 9(2):216–222.  1995.  A short essay in a creationist technical journal by a young-earth creationist paleontologist, whose author box gives an M.A. and a Ph.D. in palaeontology from Harvard.  It defines stratigraphic, morphological and stratomorphic intermediates, grants that the fossil record confirms the higher-level series that evolution predicted, sketches a Flood model that might account for some of them, and names the whales as the series it cannot yet explain.  This page uses it because it is the young-earth side's own most candid assessment of these sequences, and because its examples sort cleanly by rank.

1. 1a.

   Page 219:  “Creationists therefore need to accept this fact.  It certainly CANNOT be said that traditional creation theory expected (predicted) any of these fossil finds.”  CANNOT is capitalised in the original, as printed.  Do not quote this sentence without its companion at p. 218, which gives the failed prediction it follows from.  Wise's footnotes source every example on his list to mainstream literature and not to creationist works, including Hopson 1994 for the mammal-like reptiles, so a reader can check his claims without touching a creationist source. ↩ ↩

2. 1b.

   Pages 218–219, section It Is a Very Good Evolutionary Argument:  Wise defines a stratomorphic series, on p. 218, as a sequence of species or higher taxa in which each is a stratomorphic intermediate between the taxa below and above it in the rock.  He then lists Darwin's fourth expectation, stratomorphic series, as confirmed by the early bird series, the tetrapod series, the whale series, the various mammal series of the Cenozoic, among them the horse, camel, elephant, pig and titanothere series, the Cantius and Plesiadapis primate series, and the hominid series.  The list begins at the foot of the right column of p. 218 and ends at the top of p. 219. ↩ ↩

3. 1c.

   Page 218, section It Is a Very Good Evolutionary Argument:  Under his own heading, the paragraph that ends in the concession opens with a failed prediction.  Of Darwin's four stratomorphic-intermediate expectations, the commonness of inter-specific stratomorphic intermediates.  “has been the most disappointing for classical Darwinists”.  .  The current lack of any certain example is what drove the development and acceptance of punctuated equilibrium.  Stripping this is the most likely way our own side misuses the passage in the other direction, by making Wise concede more than he did. ↩

4. 1d.

   Page 220, right column:  “Given further that the within-group morphology differences are within taxonomic families, it is likely that the differences are intra-baraminic in every case.”  This is the rank rule for the Cenozoic mammal series generally, stated by the same author who states the whale problem, in the same article, one page after the whale paragraph on p. 219. ↩ ↩

5. 1e.

   Page 219, section It Appears Explainable in the Creation Model:  Wise sketches a creationist history in which a transgressing Flood buried plant and animal communities in the order it met them.  He suggests that many stratomorphic intermediates were geographic intermediates, animals of intermediate form living where two adjacent biozones met, buried as stratigraphic intermediates by the rising water, and he names the early tetrapod series, the mammal-like reptiles and the bird series.  The few that remain, among them the archaeocetes, he suggests may be morphological intermediates that reached their place in the rock by accident.  The whale paragraph that follows, in the right column of the same page, calls the whales the largest challenge. ↩ ↩

6. 1f.

   Page 220, section It Offers Encouragement to the Creationist Model:  Wise says the mammal-like reptiles.  “are stratigraphically between the oldest mammals and the oldest reptiles, making them a good higher-taxon stratomorphic intermediate”.  , and.  “the three jaw bones show a virtually monotonic change from the subequal size of the three bones of the reptile jaw towards the single bone of the mammal jaw”.  .  His references 76 and 77 both read.  “Hopson, Ref. 31”.  , which is J. A. Hopson, Synapsid evolution and the radiation of non-eutherian mammals, in Major Features of Vertebrate Evolution, ed. D. R. Prothero and R. M. Schoch, Short Courses in Paleontology 7 (Knoxville: Paleontological Society, 1994), 190–219.  This is the passage that belongs in this article, and it is almost never quoted. ↩

7. 1g.

   Page 219:  “At this point in time, the largest challenge from the stratomorphic intermediate record appears to this author to come from the fossil record of the whales.” ↩

8. 1h.

   Page 219, right column:  “At present creation theory has no good explanation for the fossil record of whales.”  There is no "the" before "whales" in this sentence; the "largest challenge" sentence higher on the page does read "of the whales."  This sentence should never be quoted without the four proposed escapes that follow it, which begin at the foot of p. 219 and run onto p. 220.  Wise is stating a problem, not conceding evolution. ↩

9. 1i.

   Page 219, right column:  The essay's own listing of the series runs Ambulocetus with the largest hind legs, "Rhodocetus" [sic, his spelling] "with hindlegs one-third smaller", Prozeuglodon "with 6 inch hindlegs", then the remaining whales "with virtually no to no hind legs"; then toothed mysticetes before baleen mysticetes, and squalodontid odontocetes with telescoped skulls and triangular teeth before modern odontocetes with telescoped skulls and conical teeth.  The author calls it "a very powerful stratomorphic series."  On the same page the essay states that the relative order of land mammals, archaeocetes and modern whales is not explainable by the conventional Flood-geology method of transgressing Flood waters. ↩ ↩

10. 1j.

    Page 218:  Wise's three definitions, verbatim in part.  A stratigraphic intermediate.  “lies stratigraphically between two other fossils or between the lowest stratigraphic representatives of two fossil groups”.  ; a morphological intermediate.  “is in some sense morphologically intermediate between two other fossils or between the shared characters of each of two other fossil groups”.  ; and a stratomorphic intermediate is one that is.  “BOTH a stratigraphic intermediate AND a morphological intermediate”.  .  His four predicted kinds are inter-specific stratomorphic intermediates, stratomorphic intermediate species, higher-taxon stratomorphic intermediates, and stratomorphic series. ↩

11. 1k.

    Pages 220–221:  The ecological-zonation proposal is paraphrased in the body rather than block-quoted.  The phrase.  “this is exactly what is seen”.  is his.  His conclusion, verbatim:  “Substantial supporting evidence of macroevolutionary theory can be found in the fossil record of stratomorphic intermediates.  Additionally, the creation model is not well enough developed at present to properly evaluate this evidence or to develop an adequate alternative scenario or explanation.” ↩

Ahlberg, Per E.  “Follow the footprints and mind the gaps: a new look at the origin of tetrapods.”  Earth and Environmental Science Transactions of the Royal Society of Edinburgh 109:115–137.  2019.  Ahlberg is a co-author of the Zachełmie paper he is defending, so his review of the objections to it is not a neutral referee's; he is also the person arguing most forcefully in print that Tiktaalik is not the ancestor, which is the opposite of a self-serving position.  A review of the fish-to-tetrapod transition by Per Ahlberg, a leading researcher in the field, which argues that tetrapods were walking on land before the end of the Middle Devonian and lived alongside the fish-like elpistostegids for at least 15 million years.  The article treats it as its single most important source, and draws its account of the Zachełmie trackways and the Devonian track sites from it.

1. 2a.

   Page 131:  Of the fossil record of the fish–tetrapod transition, he writes:  “is actually very poor and consists mostly of gaps.”  He calls this the single most important message of his survey. ↩ ↩ ↩

2. 2b.

   Page 131:  The idea that Tiktaalik was an immediate predecessor of the tetrapods:  “must thus be discarded if the footprint evidence is accepted”.  He recasts Tiktaalik and Elpistostege as late survivors of the elpistostegid radiation, and notes that the idea he is discarding was promulgated both in the scientific literature and in innumerable popular presentations. ↩

3. 2c.

   Page 132:  The elpistostegids are completely absent from the fossil record during the Eifelian and early Givetian, and Ahlberg states there is no evidence as to where they were. ↩

Lightner, Jean K. et al.  “Determining the Ark Kinds.”  Answers Research Journal 4:195–201.  2011.  A paper in the journal of Answers in Genesis, setting out how its authors will work out which animals were the "kinds" on Noah's Ark.  Where hybrid data is lacking, the authors use a method called the cognitum to find obvious groupings, and if a grouping looks too high in the classification they use the family level as the default.  The article uses it as the young-earth side's own statement that a created kind is usually the family, quoted from its own journal.

1. 3a.

   Page 198:  The paper's own statement, which it attributes to earlier baraminology work.  “From previous work in baraminology, researchers have suggested that the level of the baramin tends to fall at or near the taxonomic level of family (Wood 2006).” ↩ ↩ ↩

Cavanaugh, D. P. et al.  “Fossil Equidae: a monobaraminic, stratomorphic series.”  Proceedings of the Fifth International Conference on Creationism, 143–153.  Creation Science Fellowship, Pittsburgh.  Edited by R. L. Ivey.  2003.  A paper for the Fifth International Conference on Creationism, whose title calls the fossil horses a monobaraminic (one created kind), stratomorphic series.  Its method, baraminic distance correlation with multidimensional scaling, is contested inside creationism.  The article cites it for its title and for its authors' stated position, not for anything in its text. ↩ ↩

Gould, Stephen Jay.  “Evolution as Fact and Theory.”  Hen's Teeth and Horse's Toes, 253–262.  W. W. Norton (New York).  1981 (edition of 1983).  Page 260:  “Transitional forms are generally lacking at the species level, but they are abundant between larger groups.”  An essay arguing that evolution is both a fact and a theory, first published in Discover in May 1981 (pp. 34–37) and reprinted as essay 19 in the 1983 book.  In it Gould sets out three arguments for evolution, and the third, transitional fossils, is where the jaw-to-ear sequence comes in.  The article uses it to answer a fair objection to how Gould is usually quoted:  "larger groups" means class in this sequence, because Gould's own worked example is this sequence. ↩

1. 5a.

   Pages 257–258:  In the same reprint Gould sets out his own positive case in three arguments:  observed evolution, the imperfections that betray a history, and transitional fossils.  On the third, transitional fossils, he writes that preserved transitions are:  “not common — and should not be, according to our understanding of evolution — but they are not entirely wanting, as creationists often claim.”  Page 258:  His worked example, over the rest of the page, is this sequence:  several jawbones reduced step by step in mammalian ancestors until they become small nubbins at the back of the jaw, then the hammer and anvil of the mammalian middle ear.  That is what fixes the rank he meant by "larger groups" at class. ↩

Lightner, Jean K.  “An Initial Estimate of Avian Ark Kinds.”  Answers Research Journal 6:409–466.  2013.  A creationist paper in the Answers Research Journal, part of the Ark Encounter project of Answers in Genesis, that tries to name the bird kinds on the Ark, the created groups from which today's animals descend.  Where evidence from crosses between species is missing, it uses a cognitum approach, which groups animals by what the human senses can recognize, and it identifies 196 putative (proposed) bird kinds covering all living bird species.  The author says the figure should be considered only a rough estimate, because the data are limited and avian taxonomic classifications shift; the article cites the paper as the published creationist statement of where the kind boundary sits.

1. 6a.

   Section Introduction:  “Generally the cognitum at the family level (which is usually fairly strong) is preferred when hybrid data is lacking, though obvious cognita surrounding this level are noted.”  Applying that rule, she identifies 196 putative bird kinds covering all living bird species.  This is the published creationist statement of where the kind boundary sits, and it is what makes the rank question in this article answerable rather than rhetorical. ↩

Reeves, Colin R.  “A Critical Evaluation of Statistical Baraminology: Part 1—Statistical Principles.”  Answers Research Journal 14:261–269.  Jul 14, 2021.  A critique of the statistics behind baraminic distance correlation and its multidimensional-scaling companion, with a second part proposing ordinary cluster analysis in their place.  Reeves is a statistician at the Applied Mathematics Research Centre, Coventry University, and writes as a creationist.

1. 7a.

   Page 261, section abstract:  “This paper will argue that these methods are based on a shaky understanding of statistical principles, and that their use ought to be abandoned.” ↩ ↩ ↩ ↩

Smith, William.  Strata Identified by Organized Fossils, Containing Prints on Colored Paper of the Most Characteristic Specimens in Each Stratum.  London: W. Arding.  1816.  A book of engraved fossils, stratum by stratum, by the English mineral surveyor who drew the map of the strata of England and Wales.  Its title page says the specimens were chosen to confirm the order of the British strata and to show how to identify each one, which is correlation by fossils with no dates in years. ↩

Oppel, Albert.  Die Juraformation Englands, Frankreichs und des südwestlichen Deutschlands, nach ihren einzelnen Gliedern eingetheilt und verglichen.  Stuttgart: Ebner & Seubert.  1856.  A monograph, issued from 1856 to 1858, that divides the Jurassic rocks of England, France and south-west Germany into thin zones, each named for a characteristic ammonite such as Ammonites planorbis, and matches the zones across the three countries.  It is the classic case of correlating distant rocks by their fossils. ↩

Wise, Kurt P., and Donna Richardson.  “What Biostratigraphic Continuity Suggests about Earth History.”  Proceedings of the Ninth International Conference on Creationism 9:611–625.  2023.  A paper by Kurt Wise, a young-earth creationist with a Harvard paleontology doctorate, and Donna Richardson, doing original quantitative work on the Paleobiology Database, the same open database this section uses.  At each of 114 globally defined stratigraphic boundaries they counted the species found in the stage just below and just above the boundary within two degrees of latitude and longitude of each other, and checked the counts at 1°, 3° and 4°.  The order article on this site calls it the strongest recent concession from inside the creationist movement and recomputes its statistic;  this page cites it for its verdict that the global column is real, which makes fossil order matched between continents open to both sides.

1. 10a.

   Page 611, section Abstract:  The authors also report that the order in which the Flood buried fossils bore no relationship to fluctuations in Flood energy, a direct hit on hydrodynamic sorting models from a creationist; they also say that index fossils and sub-erathem stratigraphic units.  “provide no more information about earth history than a relative time scale.”  A relative time scale is precisely what this article needs, so that sentence is a concession rather than a rebuttal. ↩ ↩

2. 10b.

   Page 623, right column:  “the global biostratigraphic column seems to be real.”  Their conclusion on the column itself. ↩

Lautenschlager, Stephan et al.  “The role of miniaturization in the evolution of the mammalian jaw and middle ear.”  Biological Reviews 92(4):1910–1940.  2017.  A review article in Biological Reviews on how the muscles that close the jaw changed during the transition from cynodont reptiles to mammals.  The authors review what is known about those muscles and test earlier hypotheses against newly documented fossils.  The article uses it for the history of the Reichert and Gaupp homology, which the review sets out in its historical section.

1. 11a.

   Section II, Historical account:  “Reichert (1837), and later Gaupp (1913), were the first to recognise the homology of the reptilian jaw joint and the mammalian middle ear elements based on embryological studies.” ↩

2. 11b.

   Section II, Historical account:  On the fossil work that followed the embryology: Watson (1912) on the jaw musculature of Cynognathus, working from an already extensive collection of Permian and Triassic synapsids; Adams (1918); and then the postwar wave that produced the actual intermediates, Diarthrognathus (Crompton 1958, 1972), Morganucodon (Rigney 1963), Probainognathus (Romer 1969, 1970). ↩

Meng, Jin, and Fangyuan Mao.  “On the earliest evolution of the mammaliaform teeth, jaw joint and middle ear.”  Clinical and Translational Medicine 14:e1768.  2024.  A review, published as a commentary, by Jin Meng and Fangyuan Mao, based on two 2024 Nature studies by Mao and colleagues.  It sets out three stages of the change from jaw joint to ear, each with a fossil that shows it: the mandibular middle ear, the transitional mammalian middle ear and the definitive mammalian middle ear, with a figure that sets the fossil series beside the mouse developmental series on one page.  The article uses it for that three-stage terminology and for the fossil sequence.

1. 12a.

   In Morganucodon the dentary–squamosal joint developed.  “as a secondary joint lateral to the articular-quadrate joint”.  so the animal.  “possesses a dual jaw joint”.  with the new joint bearing the load while the old one shifted toward hearing. ↩

Paleobiology Database.  Valid genus count query, taxa/list.json?base_name=X&rank=genus&status=valid.  n.d.  Retrieved Aug 3, 2026.  Counts of valid genera from the same database, using its own clade hierarchy.  Synapsida has 9,634 valid genera and Mammalia 8,825; therefore non-mammalian synapsids number 809, of which 709 are non-mammalian therapsids, 225 are non-mammalian cynodonts, and 59 are mammaliaforms that are not mammals.  Each figure is the containing clade's count minus Mammalia's.  A named genus is not an independent data point of equal weight:  some of the 809 are known from a single tooth, and the database records what has been published, including taxa later sunk into synonymy or reassigned.  The count establishes that the field is dense, not that every genus is well founded.  The article uses it that way, and notes that the specimen counts are the more honest measure, showing both ends of the range:  thousands of specimens for Morganucodon and one skull for Hadrocodium. ↩

iDigBio.  Catalogued fossil records by genus, search/records and summary/top/records.  n.d.  Retrieved Aug 2, 2026.  An aggregator of digitised museum collection records.  Two things must be stated wherever these numbers are used:  an iDigBio record is one catalogued museum object, usually one bone, tooth or jaw, not one animal, and it cannot be added to a Paleobiology Database occurrence count, which records a taxon in a collection.  Its holdings are overwhelmingly North American and British, and Chinese, Russian, South African, Brazilian and Argentine collections are largely absent, so a zero means not digitised here, never that no specimens exist.  Morganucodon has 7,636 catalogued records, 7,460 of them at the Natural History Museum (NHMUK) and 7,459 of those from the United Kingdom; GBIF, the Global Biodiversity Information Facility, returns the identical 7,636.  Kuehneotherium has 1,465 records in iDigBio and 1,307 in GBIF, and Dimetrodon has 2,522.  Sampled records are individually numbered specimens such as NHMUK PV M 109031 to PV M 109035, all Morganucodon watsoni from Pontalun 3 fissure, Pontalun (Lithalun) Quarry, Ewenny, south of Bridgend, South Wales.  The article uses the counts only where they are large and positive and therefore safe as lower bounds, to test the claim that the sequence rests on scraps arranged by an evolutionist. ↩

Paleobiology Database.  Taxa list query, taxa/list.json?taxon_name=….  n.d.  Retrieved Aug 3, 2026.  The database's own Linnaean rank codes for the groups in this sequence.  Its codes put Reptilia and Mammalia at class (17), Synapsida at subclass (16), Pelycosauria at order (13), Cynodontia at infraorder (11), and Therapsida, Probainognathia and Mammaliaformes at 25, an unranked clade.  So in the ranked scheme the database carries, the sequence starts in an order and ends in a class, the same rank distance as fish-to-tetrapod or reptile-to-bird, and four ranks above the family level where creationist baraminology is comfortable.  The article uses these codes to show how far apart the start and end of the sequence sit in the database's own ranks. ↩

Wilken, Alec T. et al.  “Biomechanics of the mandibular middle ear of the cynodont Thrinaxodon.”  Proceedings of the National Academy of Sciences 122:e2516082122.  2025.  A 2025 research article that built a finite-element model, a computer simulation of how the structure vibrates, of the jaw-joint ear bones and a soft-tissue eardrum of Thrinaxodon, a cynodont about 250 million years old.  The modelled specimen is UCMP V40466, with the retroarticular process of BP/1/7199 grafted digitally onto its articular.  The numbers as reported are a finite-element range at 38 dB SPL of 10–2,325 Hz for tympanum stimulation alone and 2,650 Hz for the whole mandibular ear, with greatest sensitivity near 1,000 Hz; an allometric range of 38–1,243 Hz, with best frequency 741 Hz from footplate area or 890 Hz from tympanum area; a hearing threshold of 28.089 dB by ancestral-state reconstruction; and an audibility criterion of 0.0052 Pa at the stapedial footplate, which substrate-borne conduction through the jaw did not meet.  The article uses it for the strongest claim the field makes about this transition and for the finding that the animal already heard through an eardrum, while noting that the eardrum is modelled rather than seen.

1. 16a.

   The evolution of the mammalian middle ear.  “is the most thoroughly documented morphological transformation in mammalian evolutionary history”. ↩

Rawson, James R. G. et al.  “Brazilian fossils reveal homoplasy in the oldest mammalian jaw joint.”  Nature 634:381–388.  2024.  A 2024 research article that scanned the lower jaws of three early synapsid groups, Brasilodon, Riograndia and Oligokyphus, with micro-CT, an X-ray method that builds three-dimensional images, and found that the dentary–squamosal jaw joint evolved more than once.  It also corrects the published account of Brasilodon, which lacks the joint.  The article uses it for the point that the jaw joint evolved more than once, and for the correction to the account of Brasilodon.

1. 17a.

   Brasilodon quadrangularis possesses neither an incipient dentary condyle nor a squamosal glenoid, contrary to previous descriptions, and its jaws articulate solely by the quadrate–articular joint.  The earlier published account, repeated for about twenty years, made Brasilodon the taxon closest to Mammaliaformes on this character.  It was wrong. ↩

Harano, Tomohiro, and Masakazu Asahara.  “Revisiting the evolutionary trend toward the mammalian lower jaw in non-mammalian synapsids in a phylogenetic context.”  PeerJ 11:e15575.  2023.  A 2023 research article that tested whether the dentary, the tooth-bearing bone of the lower jaw, steadily enlarged at the expense of the postdentary bones across non-mammalian synapsids.  The authors measured the dentary and lower-jaw area and length in lateral view from published illustrations of 53 taxa, 41 of them therapsids; areas were obtainable for 43, four landmarks were digitised in tpsDig and the areas measured in ImageJ, and the measurements were log-transformed and fitted by phylogenetic generalised least squares on a majority-rule consensus of the 60 time-scaled trees of Jones, Angielczyk and Pierce (2019), with eight models of trait evolution compared by AIC, including Brownian motion with a directional trend parameter.  Relative dentary area shows a significant trend (trend 0.005, t = 3.246, P = 0.002, with the trend model best supported), but relative dentary length does not (Dentary Length 1: trend 0.005, t = 1.896, P = 0.064, with trend and Brownian motion equally supported; Dentary Length 2: trend 0.000, t = −0.166, P = 0.869, with Pagel's lambda 0.804 and kappa 0.341 best supported), and the dentary scales almost isometrically with the whole jaw in every regression, so miniaturisation does not explain the area trend.  The article uses it to test the claim that the dentary steadily grew while the postdentary bones shrank, a claim that the authors' results do not support for length.

1. 18a.

   “Our results provide no evidence of an evolutionary trend toward the dentary enlargement at the expense of postdentary bones across non-mammalian synapsids.”  Their inference is that the area trend reflects vertical expansion of the dentary, a taller front end and a more developed coronoid process, both of which increase muscle attachment area and bite force, rather than reduction of the postdentary region, and that the postdentary reduction belongs to the transition from non-mammalian cynodonts to early mammals rather than to synapsid history as a whole. ↩

Nature.  Editorial summary accompanying Niedźwiedzki et al. (2010).  2010.  The journal's own editorial summary of the 2010 trackway paper, written on the day of publication, so it is the journal speaking in its own voice, not a creationist gloss.  It says the finds "suggest that the elpistostegids that we know were late-surviving relics rather than direct transitional forms, and they highlight just how little we know of the earliest history of land vertebrates."  The article uses it because the journal itself drew the consequence for the known fish-like intermediates. ↩

Qvarnström, Martin et al.  “Non-marine palaeoenvironment associated to the earliest tetrapod tracks.”  Scientific Reports 8:1074.  2018.  A 2018 study by four of the five authors of the 2010 trackway paper, reinterpreting the rocks at Zachełmie Quarry in Poland that hold the earliest tetrapod tracks.  It used new field data from the three track horizons and a restudy with 34 thin sections, which are very thin slices of rock examined under a microscope.  It concludes that the track beds formed in temporary lakes, not a marine shore, so the trackmaker could walk on land, and the article uses it as the discovery team's own revision of the marine reading, including the weaknesses its authors admit.

1. 20a.

   Page 1:  The tracks are given as.  “approximately 390 million years old”.  The earliest definite tetrapod body fossils are stated to be about 14 million years younger than the tracks.  Panderichthys is stated to be contemporary with the Valentia Island tracks and therefore about 5 million years younger than Zachełmie. ↩

Paleobiology Database.  n.d.  A public database of published fossil finds, each recorded with a taxon, a place and an age bracket rather than a single age.  It records what has been published, so it measures the literature as much as the rocks, and it grows, so a later count runs higher.  The counts on this page were made for the child articles in August 2026, and each article prints its own queries.

1. 21a.

   The query returned 5,986 occurrences, and none has a maximum age older than 66 million years.  That confirms a claim Kurt Wise made in 1995 from the printed literature, against a 2026 compilation that did not exist when Wise made it, and confirming the claim deepens the young-earth problem rather than easing it.  Two records touch exactly 66 Ma, but they are coarse bin assignments for Basilosaurus entries labelled "Tertiary" and "Paleogene", not pre-Cenozoic finds.  The oldest resolved records are Himalayacetus subathuensis and Pakicetus attocki, both binned Ypresian at 56–48.07 Ma. ↩

2. 21b.

   85 valid family-rank names under Cetacea, some of them synonymy noise but the great majority real. ↩

3. 21c.

   Equidae, counted for the horse article on 3 August 2026:  6,517 occurrence records, 51 accepted genera, and 288 accepted species out of 440 names ever proposed.  The stratigraphic bounds are the limits of the containing time interval, so the article uses them only to put the genera in order. ↩

4. 21d.

   Valid genera counted for the bird article on 3 August 2026:  971 non-avian theropod genera in 138 families, and 1,884 avian genera in 341 families in the fossil record. ↩

Gingerich, Philip D.  “Land-to-sea transition in early whales: evolution of Eocene Archaeoceti (Cetacea) in relation to skeletal proportions and locomotion of living semiaquatic mammals.”  Paleobiology 29(3):429–454.  2003.  A research paper in Paleobiology, a journal of the Paleontological Society, by the paleontologist who named or co-named many of the genera its table lists.  It measured 14 trunk and limb dimensions in 50 living semiaquatic mammals, then added an anthracothere and two archaeocete whales to compare with them, and found that the rates of change in both phases of the move from land to sea were about an order of magnitude (roughly ten times) higher than background rates for that timescale.  The article uses it as its main table of the archaeocete fossils and as the source for its rate calculation, and it quotes the author's statement that the rates were higher than the author expected.  Mirror:  Archive.org

1. 22a.

   Table 1, page 430:  “Classification of genera in five families of Archaeoceti … Summary of known skeletal remains is provided in the right-hand column.”  Thirty genera.  Graded "Virtually complete skeleton": Basilosaurus and Dorudon, both Basilosauridae.  Graded from teeth, a partial dentary or vertebrae alone: Nalacetus, Himalayacetus, Gandakasia, Pappocetus, Natchitochia, Pontogeneus, Basiloterus.  The remaining twenty-one are "skull and partial skeleton," "partial skull," or similar.  Gingerich named or co-named twelve of the thirty genera in the table, counted from its authority column. ↩

2. 22b.

   Page 447:  The paper describes the Rodhocetus-to-Dorudon step as.  “more profound than the first in that the distance traveled was greater and the full spectrum of semiaquatic locomotor morphologies was crossed.”  The author is naming a gap in the sequence the author built, in print, in a peer-reviewed journal, sixteen years before it was filled. ↩

Gingerich, Philip D. et al.  “Aegicetus gehennae, a new late Eocene protocetid (Cetacea, Archaeoceti) from Wadi Al Hitan, Egypt, and the transition to tail-powered swimming in whales.”  PLoS ONE 14(12):e0225391.  2019.  A 2019 description of a new late Eocene protocetid (an early whale family) from Wadi Al Hitan in Egypt, with a nearly complete vertebral column, rib cage and limbs, and an estimated body weight of about 890 kg.  The authors judge it more fully aquatic than earlier protocetids and say it is doubtful that it had a tail fluke.  The article uses the paper for its measurements of tail flukes in modern and extinct whales, and for the authors' own finding that the animal was thoroughly aquatic.

1. 23a.

   Figure 26:  Caption.  “Thus it is questionable whether Dorudon and Basilosaurus were tail-powered swimmers.  A small fluke on a relatively long body may have served, initially, as a caudal stabilizer.”  Context warning: in the body text directly above the figure he adds that it is questionable whether such short flukes on the bodies of long archaeocetes could provide enough surface area to power a large volume and mass through water.  He is arguing about the mode of propulsion, not about whether these animals were aquatic.  An article that quotes it to suggest that even the fully aquatic whales might not have been whales is misusing it. ↩

2. 23b.

   Section Abstract:  The new animal has a vertebral column complete from C1 through Ca9, a vertebral formula of 7:15:4:4:9+, a nearly complete rib cage and sternum, both fore and hind limbs, and an estimated body weight of about 890 kg.  The abstract describes it as.  “more fully aquatic and less specialized as a foot-powered swimmer than earlier protocetids”.  and says of the animal itself:  “It is doubtful that A. gehennae had a tail fluke”.  Section Geological setting and age:  The horizon is.  “near the base of the Gehannam Formation”.  at Wadi Al Hitan. ↩

Wood, Todd C.  “Using creation science to demonstrate evolution? Senter's strategy revisited.”  Journal of Evolutionary Biology 24(4):914–918.  2011.  A technical reply, in the same journal, to Senter's 2010 paper, written by Todd Wood, a young-earth creationist with a PhD in biochemistry from the University of Virginia and one of the two principal developers of statistical baraminology.  The article cites it directly rather than through any secondary account, because it is a creationist's technical reply printed in a mainstream evolutionary journal.

1. 24a.

   From the abstract:  “Distance correlation using Senter's set of taxa and characters supports his conclusion of morphological continuity, but other sets of taxa with more characters do not.”  The first clause is the concession this article is built on and is almost never quoted on either side. ↩

Garner, Paul A. et al.  “Baraminological analysis of Jurassic and Cretaceous Avialae.”  Proceedings of the Seventh International Conference on Creationism, art. 7 7.  2013.  A creationist baraminology study of Jurassic and Cretaceous Avialae, the group of birds and their extinct relatives, by Paul Garner, Todd Wood and Marcus Ross.  Baraminology is a creationist method for sorting organisms into created kinds.  The cited page is the Biblical Creation Trust's project page, cited instead of the paper.  It carries the authors' own technical summary of their result, a primary statement of what they found rather than a critic's characterisation, and the article says so rather than implying otherwise.  The summary reports discontinuities between most Avialae and the Deinonychosauria (Troodontidae and Dromaeosauridae), and clustering of some Avialae with dinosaurs in four of the analyses.  Its six input matrices are Chiappe 2001, Clarke & Norell 2002, Zhou et al. 2008, O'Connor et al. 2009, Senter 2011 and Xu et al. 2011, and the article cites it for the authors' own statement that some extinct feathered animals may be kinds of dinosaurs.

1. 25a.

   Plain-language summary at the head of the project page:  “Modern birds and dinosaurs fall into separate created kinds, consistent with the claims of the Bible.  However, some extinct feathered animals (such as the famous Archaeopteryx) may be kinds of dinosaurs.” ↩

Hartman, Scott et al.  “A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight.”  PeerJ 7:e7247.  2019.  A 2019 description of Hesperornithoides miessleri, a new paravian dinosaur from the Morrison Formation of Wyoming, and a much larger analysis of the maniraptorans, the dinosaur group that includes birds.  The animal is a troodontid (Paleobiology Database range Kimmeridgian–Tithonian), at essentially the same level as Archaeopteryx but on a different continent.  The article uses it as a check that does not depend on the Chinese material.

1. 26a.

   The phylogenetic results, in the authors' words.  Making archaeopterygids sister to dromaeosaurids costs four more steps.  In the authors' preferred topology, once the new Archaeopteryx and Anchiornis data are included, Archaeopteryx nests inside the anchiornithine clade and the whole group is recovered as deinonychosaurs, the same result Xu reported in 2011, reached independently.  “both the traditional Archaeopteryx position closer to Aves and the common Anchiornis position sister to troodontids require a single additional step each.” ↩

Longrich, Nicholas R. et al.  “Mass extinction of birds at the Cretaceous–Paleogene (K–Pg) boundary.”  PNAS 108(37):15253–15257.  2011.  A paleontology paper in PNAS that reexamines the birds of the latest Cretaceous in western North America, from the Hell Creek Formation of Montana and the Dakotas, the Lance Formation of Wyoming, and the Frenchman Formation of Saskatchewan.  The authors say these are the only diverse bird fossils that can be confidently dated to the end of the Maastrichtian.  They identify seventeen species, seven of them archaic birds, and find that the archaic birds persisted to within 300,000 years of the boundary.  The article calls it the best-constrained data on the extinction.  Its stratigraphic claim is ordinal: these lineages occur below the boundary layer and never above it, in the same basin and the same columns, which is superposition and does not require the magnetostratigraphic and radiometric constraints the paper also reports.  Mirror:  PMC

1. 27a.

   Section Discussion:  The authors say four lineages of archaic birds persisted to the boundary.  They add that definitive archaic birds have never been reported from the Paleogene, and that their own examination of North American Paleocene material found none.  “Enantiornithes, Hesperornithes, Ichthyornithes, and Palintropiformes.  These four clades are a major part of the fauna, comprising 7 of the 17 species (41%) recognized here.” ↩

2. 27b.

   Section Discussion:  “we could not definitively refer any of these fossils to the avian crown; thus claims of a major neornithine radiation in the Cretaceous are not at present supported by the fossil record.  One of these species, Ornithurine C, is known from the Paleocene and therefore represents the only Maastrichtian bird known to cross the K–Pg boundary.” ↩

3. 27c.

   Section Discussion:  The conclusion, the last paragraph of the Discussion, says that the evidence is consistent with a major extinction of archaic birds at the boundary,  “which may have provided an ecological release, permitting the radiation of modern birds in the Paleogene.”  The article treats this as a complete naturalistic explanation of the same pattern, and any creationist use of the pattern has to answer it rather than ignore it. ↩

Gould, Stephen Jay.  “Life's Little Joke.”  Natural History 96(4).  Apr 1987 (edition of 1991).  An essay first published in Natural History in April 1987 and reprinted on pages 168–181 of Bully for Brontosaurus: Reflections in Natural History (W. W. Norton, New York, 1991).  The article uses it for Gould's passage on the ladder diagram of evolution, which creationists quote in part.

1. 28a.

   Page 180:  The two clauses after the dash are the ones normally cut, and they carry Gould's conclusion. ↩ ↩

Froehlich, David J.  “Quo vadis eohippus? The systematics and taxonomy of the early Eocene equids (Perissodactyla).”  Zoological Journal of the Linnean Society 134:141–256.  2002.  A taxonomic study of the early Eocene horse-family fossils, which sorts out the names and relationships of the species and genera given to them.  It analysed 40 taxa (named groups) and 121 characters (traits) and rebuilt the family tree they form.  The paper runs 116 pages.  Its introduction, pp. 142–143, sets out the history of the horse ladder step by step, each step with its original citation, and the article's history of the ladder relies on that account. ↩

Bergman, Jerry.  “The Horse Evolution Icon Exposed.”  Creation Research Society Quarterly 61:133–145.  2024.  A review, in a journal of the Creation Research Society, of the horse series, the ladder diagram of horse evolution that many textbooks still use.  It argues that the diagram is inaccurate, and that the fossil record shows a great variety of horses rather than a straight line of descent.  The article checks its claims one by one. ↩

Li, Chun et al.  “An ancestral turtle from the Late Triassic of southwestern China.”  Nature 456:497–501.  2008.  A 2008 Nature paper that described Odontochelys semitestacea, a Late Triassic turtle from southwestern China with a fully formed belly shell (plastron) but only the neural plates of a back shell (carapace).  The article uses it because its authors concluded that the belly shell came first, and that the shell is not built from fused skin bones, since this turtle has none.

1. 31a.

   “The new species shows that the plastron evolved before the carapace and that the first step of carapace formation is the ossification of the neural plates coupled with a broadening of the ribs.”  The rest of the abstract, paraphrased: the plastron is fully developed while the carapace is neural plates only; the dorsal ribs are expanded; osteoderms (bony plates that form in the skin) are absent, which is why the authors conclude the shell is not built from fused skin bones; the pattern matches early embryonic stages of carapace formation in living turtles; and their phylogenetic analysis places Odontochelys basal to all known turtles, fossil and living. ↩

Smithson, Timothy R. et al.  “Earliest Carboniferous tetrapod and arthropod faunas from Scotland populate Romer's Gap.”  PNAS 109(12):4532–4537.  2012.  Their own statement of the prior position, paraphrased from the abstract: before this work only two localities anywhere had produced Tournaisian tetrapod specimens, one in Scotland with a single articulated skeleton and one in Nova Scotia with isolated bones, many of uncertain identity.  PubMed ID 22393016.  A 2012 PNAS paper by four researchers from the University Museum of Zoology in Cambridge and the University of Southampton.  It reports new Tournaisian (earliest Carboniferous) fossils of tetrapods (four-limbed animals) and arthropods from Scotland.  The article uses it because it is the paper that filled Romer's Gap, the gap in the fossil record that A. S. Romer recognised in 1956.

1. 32a.

   “We conclude that the gap in the fossil record has been an artifact of collection failure.” ↩

Garberoglio, Fernando F. et al.  “New skulls and skeletons of the Cretaceous legged snake Najash, and the evolution of the modern snake body plan.”  Science Advances 5(11):eaax5833.  2019.  “Morphological and molecular analyses including the new cranial data provide robust support for an extensive basal radiation of early snakes with hindlimbs and pelves, demonstrating that this intermediate morphology was not merely a transient phase between limbed and limbless body plans.”  “is hampered by the very limited fossil record of early snakes.”  A research paper that used micro-computed tomography, a three-dimensional X-ray scan, on the first three-dimensionally preserved skulls of Najash, a legged snake from the Cenomanian rocks of Patagonia, Argentina.  It reports eight new skulls and three articulated postcranial specimens, and a new family tree of early snakes.  It finds that early snakes with hindlimbs and pelves formed a broad group, not a passing stage between limbed and limbless snakes.  The article reads the authors' admission about the small fossil record as a claim about sampling. ↩

Simmons, Nancy B. et al.  “Primitive Early Eocene bat from Wyoming and the evolution of flight and echolocation.”  Nature 451:818–821.  2008.  The authors say the pathways to flapping flight and echolocation.  “have been in dispute, and until now fossils have been of limited use”.  The rest of the abstract, paraphrased: the changes evolved incrementally; the wing shape suggests that an undulating gliding-fluttering flight style may be primitive for bats; a long calcar (the spur that stiffens the tail membrane) shows that a broad tail membrane evolved early, probably as an airfoil rather than a prey-capture device; and limb proportions plus claws retained on all digits indicate an agile climber that moved quadrupedally and hung under branches.  PubMed ID 18270539.  A 2008 Nature paper describing Onychonycteris finneyi, an early Eocene bat from the Green River Formation of Wyoming.  The article uses it for the list of primitive features in a flying animal, such as claws on all of its digits.

1. 34a.

   “Forelimb anatomy indicates that the new bat was capable of powered flight like other Eocene bats, but ear morphology suggests that it lacked their echolocation abilities, supporting a 'flight first' hypothesis for chiropteran evolution.”  The second half of that sentence is what Veselka et al. 2010 challenged, and Simmons et al. 2010 defended. ↩

Ezcurra, Martín D. et al.  “Enigmatic dinosaur precursors bridge the gap to the origin of Pterosauria.”  Nature 588:445–449.  2020.  “substantially shortens the temporal and morphological gap”.  A research paper by Martín D. Ezcurra and 16 co-authors, using new cranial material, micro-CT scans of fragile skull bones and reliably associated postcrania.  Paraphrasing the rest of the abstract, the authors recover the lagerpetids, cursorial (built for running) and non-volant (unable to fly) dinosaur precursors, as the sister group of the pterosaurs, sharing numerous shared derived features (synapomorphies) across the whole skeleton.  They say this substantially shortens the temporal and morphological gap.  The neuroanatomical features related to the enhanced sensory abilities of pterosaurs are already present in lagerpetids, indicating that those features evolved before flight.  The article uses it for the lagerpetid link and for the claim that those brain features came before flight. ↩

Computed for the missing-transitions article against the full Paleobiology Database occurrence dump of 2,001,053 records, re-derived on 8 August 2026.  Each occurrence carries an age bracket, not a point age, so only occurrences whose whole bracket falls inside a single international stage are used, and a loosely dated collection cannot invent or fill a gap.  Genera found in three or more distinct stages are eligible.  An internal gap is a stage between a genus's oldest and youngest occupied stage with no recorded occurrence of that genus.  Result:  16,804 eligible genera, 75.9% with at least one internal gap, median gap 6.8 Myr.  Two limits go with the figure:  the bulk data carry no preservation flag, so trace and form taxa cannot be excluded and the extreme long-gap tail is contaminated, though the median is not;  and the database records published occurrences, so it measures the literature rather than the rocks. ↩ ↩

Jenkins, Xavier A. et al.  “The phylogenetic origin of turtles.”  Current Biology.  May 28, 2026.  Published online 28 May 2026 and in print in June 2026, with PubMed ID 42208530.  The authors report that Eunotosaurus has many primitive features and lacks crown-reptile synapomorphies, while Proganochelys, which they call one of the oldest uncontentious stem turtles, resembles archosauromorphs, especially in the endocranium.  They report strong support for turtles as sister to Archosauria (the group that includes crocodiles and birds), placing turtle origins among the earliest archosauromorphs in the late Permian.  A 2026 Current Biology paper that scanned Eunotosaurus and candidate stem turtles with X-ray computed microtomography (a three-dimensional scan of the inside of the bone) and built a family tree from the results.  The article uses it to show that the base of the turtle sequence has moved, which reopens a gap at the bottom.

1. 37a.

   “Our comprehensive phylogenetic analysis recovers Eunotosaurus as a millerettid stem reptile not related to turtles.”  The next sentence in the article's Part 1, about convergent fossorial ecologies, is also the authors'.  In the original it is separated from this one by one intervening sentence stating that the shared features, notably broadened dorsal ribs, evolved independently. ↩

Sarfati, Jonathan.  “Arguments we think creationists should NOT use.”  Creation Ministries International.  Feb 7, 2006.  A list by Creation Ministries International, by-lined Jonathan Sarfati, of arguments that its own writers think creationists should not use, each with the reasons given.  It is dated 7 February 2006 and has been updated since.  The flat claim that there are no transitional fossils is listed as unsafe, with replacement wording supplied, because candidates exist even if they are disputed and the flat form invites a comeback.  Answers in Genesis published the list first, from 2001;  CMI, the former Answers in Genesis–Australia, separated from it in 2005–2006 and kept the list. ↩

Marjanović, David, and Michel Laurin.  “Phylogeny of Paleozoic limbed vertebrates reassessed through revision and expansion of the largest published relevant data matrix.”  PeerJ 6:e5565.  2019.  A 2019 PeerJ re-analysis of the largest published data matrix for early limbed vertebrates, which the authors revised and expanded.  Marjanović examined the only known Casineria specimen in person.  Their analyses place it in a gephyrostegid–chroniosuchian grade, far from amniote origins, and they find it and Caerorhachis indistinguishable in the matrix, echoing Pawley 2006, and raise synonymy as a serious possibility.  The article uses it because it re-examines the 1999 argument, which leaned on the vertebrae and the claws, and finds the claws blunt.

1. 39a.

   On the terminal phalanges, the last bones of the digits.  “are neither pointed as expected of a claw, nor rounded as incorrectly shown in the interpretative drawing by Paton, Smithson & Clack (1999: fig. 3b).  Instead, their ends are squared off”. ↩

Long, John A. et al.  “Earliest amniote tracks recalibrate the timeline of tetrapod evolution.”  Nature 641:1193–1200.  2025.  A 2025 Nature paper that reports clawed footprints from the early Tournaisian Snowy Plains Formation in Victoria, Australia, made by a crown-group amniote (the modern lineage that includes living reptiles, birds and mammals).  The article uses it as the newest work saying that the Devonian tetrapod record is much less complete than has been thought.

1. 40a.

   “It seems that tetrapod evolution proceeded much faster, and the Devonian tetrapod record is much less complete, than has been thought.”  The paper reports early Tournaisian clawed trackways from the Snowy Plains Formation in Victoria, Australia, attributed to a crown-group amniote, and concludes that crown amniotes are 35–40 million years older than thought and that all stem-tetrapod and stem-amniote lineages must have originated during the Devonian.  The paper was one year old when checked, has drawn no published response, and is a trackway claim without body fossils. ↩